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1. Irradiance and cloud optical properties from solar photovoltaic systems

Author: J. Barry, S. Meilinger, K. Pfeilsticker, A. Herman-Czezuch, N. Kimiaie, C. Schirrmeister, R. Yousif, T. Buchmann, J. Grabenstein, H. Deneke, J. Witthuhn, C. Emde, F. Gödde, B. Mayer, L. Scheck, M. Schroedter-Homscheidt, P. Hofbauer, and M. Struck
Subjects: Environmental engineering, TA170-171, Earthwork. Foundations, TA715-787
Abstract: Solar photovoltaic power output is modulated by atmospheric aerosols and clouds and thus contains valuable information on the optical properties of the atmosphere. As a ground-based data source with high spatiotemporal resolution it has great potential to complement other ground-based solar irradiance measurements as well as those of weather models and satellites, thus leading to an improved characterisation of global horizontal irradiance. In this work several algorithms are presented that can retrieve global tilted and horizontal irradiance and atmospheric optical properties from solar photovoltaic data and/or pyranometer measurements. The method is tested on data from two measurement campaigns that took place in the Allgäu region in Germany in autumn 2018 and summer 2019, and the results are compared with local pyranometer measurements as well as satellite and weather model data. Using power data measured at 1 Hz and averaged to 1 min resolution along with a non-linear photovoltaic module temperature model, global horizontal irradiance is extracted with a mean bias error compared to concurrent pyranometer measurements of 5.79 W m−2 (7.35 W m−2) under clear (cloudy) skies, averaged over the two campaigns, whereas for the retrieval using coarser 15 min power data with a linear temperature model the mean bias error is 5.88 and 41.87 W m−2 under clear and cloudy skies, respectively. During completely overcast periods the cloud optical depth is extracted from photovoltaic power using a lookup table method based on a 1D radiative transfer simulation, and the results are compared to both satellite retrievals and data from the Consortium for Small-scale Modelling (COSMO) weather model. Potential applications of this approach for extracting cloud optical properties are discussed, as well as certain limitations, such as the representation of 3D radiative effects that occur under broken-cloud conditions. In principle this method could provide an unprecedented amount of ground-based data on both irradiance and optical properties of the atmosphere, as long as the required photovoltaic power data are available and properly pre-screened to remove unwanted artefacts in the signal. Possible solutions to this problem are discussed in the context of future work.
Published: 2023
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2. Surface solar irradiation retrieval from MSG/SEVIRI based on APOLLO Next Generation and HELIOSAT‑4 methods

Author: M. Schroedter-Homscheidt, F. Azam, J. Betcke, N. Hanrieder, M. Lefèvre, L. Saboret, and Y.‑M. Saint-Drenan
Subjects: apollo next generation, apollo_ng, heliosat‑4, surface irradiation, solar, global horizontal irradiation, direct irradiation, satellite-based, seviri, cams, Meteorology. Climatology, QC851-999
Abstract: This study investigates the optimum usage of the new APOLLO Next Generation (APOLLO_NG) cloud retrieval scheme in the Heliosat‑4 solar surface irradiance retrieval scheme. APOLLO_NG replaces the previously used APOLLO scheme and introduces a probabilistic cloud mask instead of binary cloud masking used previously. A cloud probability threshold of 1 % was found optimal for the usage of the Heliosat‑4 cloud scheme. For direct irradiances, the use of an apparent optical depth in optically thin as well as in optically thick, but broken cloud conditions, was investigated. While for thin clouds the cloud optical thickness (COT) modification factor as known from literature was confirmed, a COT modification factor of 0.2 for optically thick, but broken clouds was identified. Furthermore, an improved calibration of the SEVIRI instrument was implemented. The updated method is applied for MSG SEVIRI observations without any additional bias-correction and validated for Europe and Africa against observations from the BSRN and EnerMENA networks. Special focus is placed on the central European region affected mainly by clouds and the North-African region with desert dust aerosols as well as clouds. The hourly SSI showed clear improvements. The relative bias of GHI ranges between −7 and 1.3 % with a mean value of −2.8 %. The relative RMSE of GHI is between 10.3 and 25.5 % and has a mean value of 13.7 %. The relative bias of DIR ranges between −16.6 and 17.8 % and has a mean value of −3.3 %. The relative RMSE of DIR is between 16.7 and 49 % with 29.7 % as mean. For European stations without strong aerosol effects but larger cloud impacts, the average relative GHI and DIR bias is −1.3 % and 3.3 % with mean relative GHI and DIR RMSE of 15.1 % and 30.6 % respectively. The presented method has been implemented into the Copernicus Atmosphere Monitoring Service (CAMS) Radiation Service v4.
Published: 2022
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3. Increasing the spatial resolution of cloud property retrievals from Meteosat SEVIRI by use of its high-resolution visible channel: implementation and examples

Author: H. Deneke, C. Barrientos-Velasco, S. Bley, A. Hünerbein, S. Lenk, A. Macke, J. F. Meirink, M. Schroedter-Homscheidt, F. Senf, P. Wang, F. Werner, and J. Witthuhn
Subjects: Environmental engineering, TA170-171, Earthwork. Foundations, TA715-787
Abstract: The modification of an existing cloud property retrieval scheme for the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument on board the geostationary Meteosat satellites is described to utilize its high-resolution visible (HRV) channel for increasing the spatial resolution of its physical outputs. This results in products with a nadir spatial resolution of 1×1 km2 compared to the standard 3×3 km2 resolution offered by the narrowband channels. This improvement thus greatly reduces the resolution gap between current geostationary and polar-orbiting meteorological satellite imagers. In the first processing step, cloudiness is determined from the HRV observations by a threshold-based cloud masking algorithm. Subsequently, a linear model that links the 0.6 µm, 0.8 µm, and HRV reflectances provides a physical constraint to incorporate the spatial high-frequency component of the HRV observations into the retrieval of cloud optical depth. The implementation of the method is described, including the ancillary datasets used. It is demonstrated that the omission of high-frequency variations in the cloud-absorbing 1.6 µm channel results in comparatively large uncertainties in the retrieved cloud effective radius, likely due to the mismatch in channel resolutions. A newly developed downscaling scheme for the 1.6 µm reflectance is therefore applied to mitigate the effects of this scale mismatch. Benefits of the increased spatial resolution of the resulting SEVIRI products are demonstrated for three example applications: (i) for a convective cloud field, it is shown that significantly better agreement between the distributions of cloud optical depth retrieved from SEVIRI and from collocated MODIS observations is achieved. (ii) The temporal evolution of cloud properties for a growing convective storm at standard and HRV spatial resolutions are compared, illustrating an improved contrast in growth signatures resulting from the use of the HRV channel. (iii) An example of surface solar irradiance, determined from the retrieved cloud properties, is shown, for which the HRV channel helps to better capture the large spatiotemporal variability induced by convective clouds. These results suggest that incorporating the HRV channel into the retrieval has potential for improving Meteosat-based cloud products for several application domains.
Published: 2021
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4. Verification of ECMWF and ECMWF/MACC's global and direct irradiance forecasts with respect to solar electricity production forecasts

Author: M. Schroedter-Homscheidt, A. Benedetti, and N. Killius
Subjects: irradiance forecast, verification, global irradiance, direct normal irradiance, scattered clouds, aerosols, MACC, Meteorology. Climatology, QC851-999
Abstract: The successful electricity grid integration of solar energy into day-ahead markets requires at least hourly resolved 48 h forecasts. Technologies as photovoltaics and non-concentrating solar thermal technologies make use of global horizontal irradiance (GHI) forecasts, while all concentrating technologies both from the photovoltaic and the thermal sector require direct normal irradiances (DNI). The European Centre for Medium-Range Weather Forecasts (ECMWF) has recently changed towards providing direct as well as global irradiances. Additionally, the MACC (Monitoring Atmospheric Composition & Climate) near-real time services provide daily analysis and forecasts of aerosol properties in preparation of the upcoming European Copernicus programme. The operational ECMWF/IFS (Integrated Forecast System) forecast system will in the medium term profit from the Copernicus service aerosol forecasts. Therefore, within the MACC‑II project specific experiment runs were performed allowing for the assessment of the performance gain of these potential future capabilities. Also the potential impact of providing forecasts with hourly output resolution compared to three-hourly resolved forecasts is investigated. The inclusion of the new aerosol climatology in October 2003 improved both the GHI and DNI forecasts remarkably, while the change towards a new radiation scheme in 2007 only had minor and partly even unfavourable impacts on the performance indicators. For GHI, larger RMSE (root mean square error) values are found for broken/overcast conditions than for scattered cloud fields. For DNI, the findings are opposite with larger RMSE values for scattered clouds compared to overcast/broken cloud situations. The introduction of direct irradiances as an output parameter in the operational IFS version has not resulted in a general performance improvement with respect to biases and RMSE compared to the widely used Skartveit et al. (1998) global to direct irradiance conversion scheme. Cloudy situations and especially thin ice cloud cases are forecasted much better with respect to biases and RMSE, but large biases are introduced in clear sky cases. When applying the MACC aerosol scheme to include aerosol direct effects, an improvement especially in DNI biases is found for cloud free cases as expected. However, a performance decrease is found for water cloud cases. It is assumed that this is caused by the lack of an explicit modelling of cloud-aerosol interactions, while other meteorological forcings for cloud processes like the temperature field are modified by the aerosols.
Published: 2017
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5. McClear: a new model estimating downwelling solar radiation at ground level in clear-sky conditions

Author: M. Lefèvre, A. Oumbe, P. Blanc, B. Espinar, B. Gschwind, Z. Qu, L. Wald, M. Schroedter-Homscheidt, C. Hoyer-Klick, A. Arola, A. Benedetti, J. W. Kaiser, and J.-J. Morcrette
Subjects: Environmental engineering, TA170-171, Earthwork. Foundations, TA715-787
Abstract: A new fast clear-sky model called McClear was developed to estimate the downwelling shortwave direct and global irradiances received at ground level under clear skies. It is a fully physical model replacing empirical relations or simpler models used before. It exploits the recent results on aerosol properties, and total column content in water vapour and ozone produced by the MACC project (Monitoring Atmosphere Composition and Climate). It accurately reproduces the irradiance computed by the libRadtran reference radiative transfer model with a computational speed approximately 105 times greater by adopting the abaci, or look-up table, approach combined with interpolation functions. It is therefore suited for geostationary satellite retrievals or numerical weather prediction schemes with many pixels or grid points, respectively. McClear irradiances were compared to 1 min measurements made in clear-sky conditions at several stations within the Baseline Surface Radiation Network in various climates. The bias for global irradiance comprises between −6 and 25 W m−2. The RMSE ranges from 20 W m−2 (3% of the mean observed irradiance) to 36 W m−2 (5%) and the correlation coefficient ranges between 0.95 and 0.99. The bias for the direct irradiance comprises between −48 and +33 W m−2. The root mean square error (RMSE) ranges from 33 W m−2 (5%) to 64 W m−2 (10%). The correlation coefficient ranges between 0.84 and 0.98. This work demonstrates the quality of the McClear model combined with MACC products, and indirectly the quality of the aerosol properties modelled by the MACC reanalysis.
Published: 2013
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6. Validation of an hourly resolved global aerosol model in answer to solar electricity generation information needs

Author: M. Schroedter-Homscheidt and A. Oumbe
Subjects: Physics, QC1-999, Chemistry, QD1-999
Abstract: Solar energy applications need global aerosol optical depth (AOD) information to derive historic surface solar irradiance databases from geostationary meteorological satellites reaching back to the 1980's. This paper validates the MATCH/DLR model originating in the climate community against AERONET ground measurements. Hourly or daily mean AOD model output is evaluated individually for all stations in Europe, Africa and the Middle East – an area highly interesting for solar energy applications being partly dominated by high aerosol loads. Overall, a bias of 0.02 and a root-mean-square error (RMSE) of 0.23 are found for daily mean AOD values, while the RMSE increases to 0.28 for hourly mean AOD values. Large differences between various regions and stations are found providing a feedback loop for the aerosol modelling community. The difference in using daily means versus hourly resolved modelling with respect to hourly resolved observations is evaluated. Nowadays state-of-the-art in solar resource assessment relies on monthly turbidity or AOD climatologies while at least hourly resolved irradiance time series are needed by the solar sector. Therefore, the contribution of higher temporally modelled AOD is evaluated.
Published: 2013
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7. Solar irradiance in clear atmosphere: study of parameterisations of change with altitude

Author: A. Oumbe, Ph. Blanc, B. Gschwind, M. Lefevre, Z. Qu, M. Schroedter-Homscheidt, and L. Wald
Subjects: Science, Physics, QC1-999, Meteorology. Climatology, QC851-999
Abstract: Parameterisation of changes of the solar irradiance at ground level with a specific variable (e.g. solar zenithal angle, aerosol optical depth, altitude, etc.) is often used in operational processes because it saves computational time. This paper deals with the modelling of the vertical profile of downwelling solar irradiance for the first two kilometres above ground in clear sky conditions. Two analytical parameterisations are evaluated for direct and global irradiance in spectral bands as well as for the total irradiance. These parameterisations reproduce the vertical profile with good accuracy for global spectral irradiance and are less accurate for direct component, especially in turbid atmosphere. A piecewise linear interpolation technique using irradiance values known at surface and 4 altitudes every 500 m performs better in any case.
Published: 2011
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8. Understanding the aerosol information content in multi-spectral reflectance measurements using a synergetic retrieval algorithm

Author: D. Martynenko, T. Holzer-Popp, H. Elbern, and M. Schroedter-Homscheidt
Subjects: Environmental engineering, TA170-171, Earthwork. Foundations, TA715-787
Abstract: An information content analysis for multi-wavelength SYNergetic AErosol Retrieval algorithm SYNAER was performed to quantify the number of independent pieces of information that can be retrieved. In particular, the capability of SYNAER to discern various aerosol types is assessed. This information content depends on the aerosol optical depth, the surface albedo spectrum and the observation geometry. The theoretical analysis is performed for a large number of scenarios with various geometries and surface albedo spectra for ocean, soil and vegetation. When the surface albedo spectrum and its accuracy is known under cloud-free conditions, reflectance measurements used in SYNAER is able to provide for 2–4° of freedom that can be attributed to retrieval parameters: aerosol optical depth, aerosol type and surface albedo. The focus of this work is placed on an information content analysis with emphasis to the aerosol type classification. This analysis is applied to synthetic reflectance measurements for 40 predefined aerosol mixtures of different basic components, given by sea salt, mineral dust, biomass burning and diesel aerosols, water soluble and water insoluble aerosols. The range of aerosol parameters considered through the 40 mixtures covers the natural variability of tropospheric aerosols. After the information content analysis performed in Holzer-Popp et al. (2008) there was a necessity to compare derived degrees of freedom with retrieved aerosol optical depth for different aerosol types, which is the main focus of this paper. The principle component analysis was used to determine the correspondence between degrees of freedom for signal in the retrieval and derived aerosol types. The main results of the analysis indicate correspondence between the major groups of the aerosol types, which are: water soluble aerosol, soot, mineral dust and sea salt and degrees of freedom in the algorithm and show the ability of the SYNAER to discern between this aerosol types. The results of the work will be further used for the development of the promising methodology of the construction error covariance matrices in the assimilation system.
Published: 2010
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9. Observation operator for the assimilation of aerosol type resolving satellite measurements into a chemical transport model

Author: M. Schroedter-Homscheidt, H. Elbern, and T. Holzer-Popp
Subjects: Physics, QC1-999, Chemistry, QD1-999
Abstract: Modelling of aerosol particles with chemical transport models is still based mainly on static emission databases while episodic emissions cannot be treated sufficiently. To overcome this situation, a coupling of chemical mass concentration modelling with satellite-based measurements relying on physical and optical principles has been developed. This study deals with the observation operator for a component-wise assimilation of satellite measurements. It treats aerosol particles classified into water soluble, water insoluble, soot, sea salt and mineral dust containing aerosol particles in the atmospheric boundary layer as separately assimilated aerosol components. It builds on a mapping of aerosol classes used both in observation and model space taking their optical and chemical properties into account. Refractive indices for primary organic carbon particles, anthropogenic particles, and secondary organic species have been defined based on a literature review. Together with a treatment of different size distributions in observations and model state, this allows transforming the background from mass concentrations into aerosol optical depths. A two-dimensional, variational assimilation is applied for component-wise aerosol optical depths. Error covariance matrices are defined based on a validation against AERONET sun photometer measurements. Analysis fields are assessed threefold: (1) through validation against AERONET especially in Saharan dust outbreak situations, (2) through comparison with the British Black Smoke and Sulphur Dioxide Network for soot-containing particles, and (3) through comparison with measurements of the water soluble components SO4, NH4, and NO3 conducted by the EMEP (European Monitoring and Evaluation Programme) network. Separately, for the water soluble, the soot and the mineral dust aerosol components a bias reduction and subsequent a root mean square error reduction is observed in the analysis for a test period from July to November 2003. Additionally, examples of an improved analysis during wildfire and dust outbreak situations are shown.
Published: 2010
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10. Improvements of synergetic aerosol retrieval for ENVISAT

Author: T. Holzer-Popp, M. Schroedter-Homscheidt, H. Breitkreuz, D. Martynenko, and L. Klüser
Subjects: Physics, QC1-999, Chemistry, QD1-999
Abstract: The synergetic aerosol retrieval method SYNAER (Holzer-Popp et al., 2002a) has been extended to the use of ENVISAT measurements. It exploits the complementary information of a radiometer and a spectrometer onboard one satellite platform to extract aerosol optical depth (AOD) and speciation (as a choice from a representative set of pre-defined mixtures of water-soluble, soot, mineral dust, and sea salt components). SYNAER consists of two retrieval steps. In the first step the radiometer is used for accurate cloud screening, and subsequently to quantify the aerosol optical depth (AOD) at 550 nm and spectral surface brightness through a dark field technique for different pre-defined aerosol mixtures. In the second step the spectrometer is applied to choose the most plausible aerosol mixture through a least square fit of the measured spectrum with simulated spectra using the mixture-dependent values of AOD and surface brightness retrieved in the first step. This method was developed and a first case study evaluation against few (15) multi-spectral ground-based AERONET sun photometer observations was conducted with a sensor pair (ATSR-2 and GOME) onboard ERS-2. Due to instrumental limitations the coverage of SYNAER/ERS-2 is very sparse. Therefore, SYNAER was transferred to similar sensors AATSR and SCIAMACHY onboard ENVISAT. While transferring to the new sensor pair significant improvements in the methodology were made based on a thorough evaluation of the methodology: (1) an update of the aerosol model, (2) improved cloud detection in the tropics and sub tropics, and (3) an enhanced dark field albedo characterization. This paper describes these improvements in detail and assesses their combined impact on the results. After a brief assessment of atmospheric noise impact on comparisons of pixel and station measurements a validation against ground-based measurements establishes error bars for the SYNAER/ENVISAT method version 2.0. A theoretical analysis of the information content with regard to aerosol composition (second retrieval step) is presented to quantify the potential and limitations of this new capability provided by the SYNAER method. Building on this analysis, first seasonal and monthly composition results calculated by applying SYNAER version 2.0 to AATSR and SCIAMACHY are shown to demonstrate the potential of the approach. An inter-comparison to earlier results of SYNAER version 1.0 is made for both the validation and the example datasets.
Published: 2008

11. Intercomparison of satellite retrieved aerosol optical depth over ocean during the period September 1997 to December 2000

Author: G. Myhre, F. Stordal, M. Johnsrud, D. J. Diner, I. V. Geogdzhayev, J. M. Haywood, B. N. Holben, T. Holzer-Popp, A. Ignatov, R. A. Kahn, Y. J. Kaufman, N. Loeb, J. V. Martonchik, M. I. Mishchenko, N. R. Nalli, L. A. Remer, M. Schroedter-Homscheidt, D. Tanré, O. Torres, and M. Wang
Subjects: Physics, QC1-999, Chemistry, QD1-999
Abstract: Monthly mean aerosol optical depth (AOD) over ocean is compared from a total of 9 aerosol retrievals during a 40 months period. Comparisons of AOD have been made both for the entire period and sub periods. We identify regions where there is large disagreement and good agreement between the aerosol satellite retrievals. Significant differences in AOD have been identified in most of the oceanic regions. Several analyses are performed including spatial correlation between the retrievals as well as comparison with AERONET data. During the 40 months period studied there have been several major aerosol field campaigns as well as events of high aerosol content. It is studied how the aerosol retrievals compare during such circumstances. The differences found in this study are larger than found in a previous study where 5 aerosol retrievals over an 8 months period were compared. Part of the differences can be explained by limitations and deficiencies in some of the aerosol retrievals. In particular, results in coastal regions are promising especially for aerosol retrievals from satellite instruments particularly suited for aerosol research. In depth analyses explaining the differences between AOD obtained in different retrievals are clearly needed. We limit this study to identifying differences and similarities and indicating possible sources that affect the quality of the retrievals. This is a necessary first step towards understanding the differences and improving the retrievals.
Published: 2005

12. Ice supersaturation as seen from TOVS

Author: K. Gierens, R. Kohlhepp, P. Spichtinger, and M. Schroedter-Homscheidt
Subjects: Physics, QC1-999, Chemistry, QD1-999
Abstract: We have analysed the upper tropospheric humidity with respect to ice (UTHi) data product obtained from the Television Infrared Observation Satellite (TIROS) Operational Vertical Sounder (TOVS) instrument onboard the National Oceanic and Atmospheric Administration NOAA-14 polar orbiting satellite. While in the production of the official UTHi product values in excess of 100% are ignored, we do not so - in view of many recent results obtained from a variety of other in-situ and remote sensing instruments showing that ice supersaturation frequently occurs in the upper troposphere. We show that TOVS is able to detect ice supersaturation at the correct locations (however, only in less than one percent of its soundings, presumably because of TOVS's low vertical resolution), and that the supersaturation follows the well known exponential behaviour. We conclude that values of UTHi in excess of saturation should not be considered a measurement error anymore. The similar re-analysis of TOVS data back to 1979 could give important insights into trends of upper tropospheric humidity.
Published: 2004

13. AB0034 Looking for a sle signature on peripheral b cell subsets: does a preponderant cd38+plasmablast-subpopulation lack cd73 as a sign of a disturbed adenosine axis?

Author: Matthias Schneider, M. Schroedter, Gamal Chehab, Georg Pongratz, Magdalena Siekierka-Harreis, and Jutta G Richter
Subjects: biology, business.industry, CD38, Adenosine, Immunoglobulin D, CD19, medicine.anatomical_structure, Immune system, immune system diseases, Immunology, medicine, biology.protein, Outpatient clinic, skin and connective tissue diseases, Memory B cell, business, B cell, medicine.drug
Abstract: Background Systemic Lupus Erythematosus (SLE) is an autoimmune disorder characterised by polyclonal Bcell activation, production of dsDNA-autoantibodies and cytokines. Subsets of Bcells play a central role in SLE-pathogenesis. The inflammatory milieu is characterised by the accumulation of adenosine, which confers immunosuppressive effects. Objectives In SLE, the role of CD73, an enzyme involved in the extracellular generation of adenosine from ATP, is not well characterised. This study aimed to characterise expression of CD73 Bcell subsets of SLE-patients as compared to healthy controls (HC). Methods Bcell subsets were characterised from peripheral blood of 23 SLE patients attending the outpatient clinic at the Rheumatology Unit of University Hospital Dusseldorf and of 15 HC by FACS. All patients fulfilled the revised SLE-criteria of ACR and were randomly collected in clinical remission state (SLEDAI 1.1±1.9). Results By comparison of Bcell subsets between SLE and HC, CD38 was dominantly expressed by SLE-patients (SLE 74.2%±12.9% vs. HC 64.2%±12.2%; p(MWU)=0.018). Furthermore, SLE-patients showed an increase in CD19 +IgD CD27+CD38 high plasmablasts (SLE 2.1%±3.4% vs HC 0,4%±0.4%, p(MWU) Conclusions Our study confirms CD38 +plasmablasts as being increased in peripheral blood from SLE patients as compared to HC. Furthermore, the data reveal a deficiency for CD73 on SLE plasmablasts, which suggests a decreased anti-inflammatory capacity of SLE plasmablasts as compared to HC, supporting the notion of a disturbed adenosine axis in SLE. On the other hand, the enlarged CD73 +exhausted memory pool in SLE could point to an accelerated flow of CD73 +B cells into an exhausted B cell fraction. These findings support the hypothesis of dysregulation of the adenosine axis in SLE even in inactive SLE patients. References [1] Szabo K, Papp G, Szanto A, Tarr T, Zeher M. A comprehensive investigation on the distribution of circulating follicular T helper cells and B cell subsets in primary Sjogren’s syndrome and systemic lupus erythematosus. Clinical and experimental immunology2016;183(1):76–89. [2] Jacobi AM, Reiter K, Mackay M, Aranow C, Hiepe F, Radbruch A, et al. Activated memory B cell subsets correlate with disease activity in systemic lupus erythematosus: delineation by expression of CD27, IgD, and CD95. Arthritis and Rheumatism2008;58(6):1762–73. [3] Deaglio S, Dwyer KM, Gao W, Friedman D, Usheva A, Erat A, et al. Adenosine generation catalyzed by CD39 and CD73 expressed on regulatory T cells mediates immune suppression. The Journal of Experimental Medicine2007;204(6):1257–65. [4] Hasko G, Linden J, Cronstein B, Pacher P. Adenosine receptors: therapeutic aspects for inflammatory and immune diseases. Nature Reviews Drug Discovery2008;7(9):759–70. Disclosure of Interest None declared
Published: 2018
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14. PS5:89 Looking for a sle signature on peripheral b cell subsets: does a preponderant cd38 positive plasmablast-subpopulation lack cd73 as a sign of a diminished b regulatory pool?

Author: M. Schroedter, Matthias Schneider, Magdalena Siekierka-Harreis, Stefan Vordenbäumen, Gamal Chehab, Georg Pongratz, and Jutta G Richter
Subjects: medicine.medical_specialty, biology, business.industry, Regulatory B cells, CD38, Adenosine, CD19, Rheumatology, medicine.anatomical_structure, immune system diseases, Internal medicine, Immunology, medicine, biology.protein, Extracellular, Outpatient clinic, skin and connective tissue diseases, business, B cell, medicine.drug
Abstract: Background Systemic Lupus Erythematosus (SLE) is an autoimmune disorder characterised by polyclonal Bcell activation, production of dsDNA-autoantibodies and cytokines. Subsets of Bcells play a central role in SLE-pathogenesis. The inflammatory milieu is characterised by the accumulation of adenosine, which confers immunosuppressive effects. In SLE, the role of CD73, an enzyme involved in the extracellular generation of adenosine from ATP, is not well characterised. This study aimed to characterise expression of CD73 B cell subsets of SLE-patients as compared to healthy controls (HC). Methods B cell subsets were characterised from peripheral blood of 23 SLE patients attending the outpatient clinic at the Rheumatology Unit of University Hospital Dusseldorf and of 15 HC by FACS. All patients fulfilled the revised SLE-criteria of ACR and were randomly collected in clinical remission state (SLEDAI 1.1±1.9). Results By comparison of B cell subsets between SLE and HC, CD38 was dominantly expressed by SLE patients (SLE 74.2%±12.9% vs HC 64.2%±12.2%; p(MWU)=0.018). Furthermore, SLE-patients showed an increase in CD19 +IgD CD27+CD38 high plasmablasts (SLE 2.1%±3.4% vs HC 0,4%±0.4%, p(MWU) Conclusion Our study confirms CD38 +plasmablasts as being increased in peripheral blood from SLE patients as compared to HC. Furthermore, the data reveal a deficiency for CD73 on SLE plasmablasts, which suggests a decreased regulatory capacity of SLE plasmablasts as compared to HC, supporting the notion of a reduced regulatory B cell pool in SLE. On the other hand, the enlarged CD73 +exhausted memory pool in SLE could point to an accelerated flow of CD73 +regulatory B cells into an exhausted B cell fraction. These findings support the hypothesis of a persistent regulatory B cell defect even in a state of SLE remission.
Published: 2018
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15. List of contributors

Author: A. Fernández-García, J. Fernández-Reche, P. Heller, U. Herrmann, N. Janotte, D. Kearney, E. Lüpfert, J. Pernpeintner, C. Prahl, L. Ramirez, M. Röger, F. Sallaberry, M. Schroedter-Homscheidt, F. Sutter, J. Wette, F. Wiesinger, and S. Wilbert
Published: 2017
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16. Methods to provide meteorological forecasts for optimum CSP system operations

Author: M. Schroedter-Homscheidt and S. Wilbert
Subjects: Service (systems architecture), 010504 meteorology & atmospheric sciences, Meteorology, Operations research, Nowcasting, ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION, 010501 environmental sciences, Service provider, Numerical weather prediction, 01 natural sciences, Terminology, Time series modeling, Model output statistics, Geography, 0105 earth and related environmental sciences
Abstract: Having seen that meteorological forecasts of DNI may help in performance assessment in CSP systems, this chapter provides an overview on DNI forecast options. Nowcasting for the upcoming few hours and forecasting for the upcoming days is treated separately. The chapter provides an introduction in meteorological basics and terminology being useful for the reader when ordering forecasts from operational meteorological centers or meteorological service providers. After that the technologies based on numerical weather prediction, statistical time series modeling, all-sky imagers, and satellites are described. Necessary postprocessing steps to be performed after obtaining the standard weather service products are discussed as well. After reading this chapter, an engineer should be capable of understanding what kinds of forecasts are routinely provided, what each forecast includes and how to use them properly.
Published: 2017
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17. Results from the first two years of VERITAS observations

Author: F. Krennrich, Wystan Benbow, J. P. Finley, R. G. Wagner, M. McCutcheon, M. Schroedter, C. M. Hui, Simon P. Swordy, Gernot Maier, R. Guenette, M. Beilicke, D. S. Hanna, Lucy Fortson, K. Ragan, S. P. Wakely, Geza Gyuk, Daniel Gall, D. Boltuch, R. A. Ong, N. Karlsson, Amanda Weinstein, Stephanie Wissel, L. Ciupik, G. Finnegan, A. W. Smith, C. Duke, Thomas Brian Humensky, E. Roache, J. S. Perkins, P. Kaaret, A. Cesarini, John L. Quinn, S. M. Bradbury, Manuel A. Bautista, D. Pandel, Martin Pohl, G. H. Sembroski, T. Weisgarber, D. Steele, and H. J. Rose
Subjects: Physics, Nuclear and High Energy Physics, Astrophysics::High Energy Astrophysical Phenomena, Dark matter, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Astronomy, Cosmic ray, Supersymmetry, Astrophysics, Cherenkov Telescope Array, Particle detector, Astrophysical jet, Observatory, Instrumentation
Abstract: The VERITAS observatory is an imaging atmospheric Cherenkov telescope array located in southern Arizona and covers an energy range between 100 GeV and 30 TeV. The VERITAS collaboration pursues a rigorous observing program that targets a range of key science objectives in astrophysics and particle physics; the understanding of the origin of cosmic rays, the search for supersymmetric dark matter self-annihilation, illuminating the connection between black holes and relativistic jets and constraints to the cosmological diffuse infrared background. We provide a summary of results from the first two years of observations with the full 4-telecope array reported at RICAP09.
Published: 2011
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18. OBSERVATIONS OF THE SHELL-TYPE SUPERNOVA REMNANT CASSIOPEIA A AT TeV ENERGIES WITH VERITAS

Author: R. G. Wagner, Gernot Maier, Stephanie Wissel, C. M. Hui, M. J. Lang, S. P. Wakely, T. B. Humensky, Daniel Gall, B. R. Smith, Geza Gyuk, Y. Butt, D. Boltuch, J. E. Ward, A. Cesarini, John L. Quinn, R. Dickherber, A. J.R. Weinstein, M. Bautista, S. Thibadeau, S. McArthur, V. A. Acciari, D. S. Hanna, David Kieda, J. P. Finley, R. A. Ong, Thomas Weisgarber, N. Karlsson, Jamie Holder, A. McCann, Martin Pohl, Wystan Benbow, T. C. Weekes, M. Beilicke, D. Steele, R. Guenette, V. Bugaev, S. LeBohec, F. Krennrich, E. Roache, P. Fortin, H. J. Rose, J. Grube, A. Furniss, S. P. Swordy, J. Millis, K. Byrum, Matthew J.A. Wood, Tulun Ergin, P. Moriarty, Nicola Galante, J. S. Perkins, M. Kertzman, S. J. Fegan, S. Vincent, M. Schroedter, G. H. Sembroski, P. T. Reynolds, Lucy Fortson, A. Varlotta, Wei Cui, D. Huang, M. Theiling, P. Cogan, T. Aune, Y. C. Chow, V. V. Vassiliev, P. Kaaret, G. Finnegan, A. W. Smith, C. Duke, J. H. Buckley, A. Konopelko, G. H. Gillanders, T. Arlen, L. Ciupik, E. Aliu, H. Krawczynski, K. Ragan, S. M. Bradbury, A. Cannon, D. Pandel, and M. McCutcheon
Subjects: Photon, Astrophysics::High Energy Astrophysical Phenomena, cosmic-rays, Shell (structure), Flux, Astrophysics, 01 natural sciences, Power law, cosmic rays, 0103 physical sciences, air cerenkov telescopes, crab-nebula, Supernova remnant, ism: individual objects (cassiopeia a), 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Cherenkov radiation, acceleration of particles, Physics, magnetic-fields, electron acceleration, particle-acceleration, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Astronomy and Astrophysics, gamma-ray emission, Cassiopeia A, gamma rays: ism, rx j1713.7-3946, 13. Climate action, Space and Planetary Science, ism: supernova remnants, a supernova, magic telescope
Abstract: We report on observations of very high energy gamma rays from the shell-type supernova remnant (SNR) Cassiopeia A with the Very Energetic Radiation Imaging Telescope Array System stereoscopic array of four imaging atmospheric Cherenkov telescopes in Arizona. The total exposure time for these observations is 22 hr, accumulated between September and November of 2007. The gamma-ray source associated with the SNR Cassiopeia A was detected above 200 GeV with a statistical significance of 8.3 sigma. The estimated integral flux for this gamma-ray source is about 3% of the Crab-Nebula flux. The photon spectrum is compatible with a power law dN/dE proportional to E(-Gamma) with an index Gamma = 2.61 +/- 0.24(stat) +/- 0.2(sys). The data are consistent with a point-like source. We provide a detailed description of the analysis results and discuss physical mechanisms that may be responsible for the observed gamma-ray emission.
Published: 2010
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19. OBSERVATION OF EXTENDED VERY HIGH ENERGY EMISSION FROM THE SUPERNOVA REMNANT IC 443 WITH VERITAS

Author: R. A. Ong, Thomas Weisgarber, S. LeBohec, S. M. Bradbury, A. Cannon, D. Pandel, D. Horan, P. Cogan, J. Grube, David Kieda, L. Ciupik, P. T. Reynolds, A. McCann, Lucy Fortson, M. Kertzman, M. K. Daniel, E. Aliu, H. Krawczynski, A. Varlotta, Gernot Maier, S. P. Swordy, V. V. Vassiliev, Martin Pohl, S. P. Wakely, Daniel Gall, K. Ragan, M. Wood, M. Beilicke, G. Finnegan, T. B. Humensky, A. W. Smith, B. Zitzer, A. Konopelko, R. G. Wagner, C. Duke, M. Schroedter, L. Valcarcel, Vikram V. Dwarkadas, P. Moriarty, Geza Gyuk, A. Weinstein, T. Arlen, P. Colin, A. N. Otte, A. Furniss, J. H. Buckley, P. Kaaret, Tulun Ergin, F. Krennrich, P. Fortin, S. Vincent, D. S. Hanna, Wystan Benbow, M. Theiling, C. M. Hui, Y. Butt, J. P. Finley, V. Bugaev, G. H. Sembroski, J. A. Toner, T. C. Weekes, R. Dickherber, A. Imran, E. Hays, J. S. Perkins, John Kildea, D. A. Williams, R. Guenette, J. Millis, O. Celik, K. Byrum, Wei Cui, Stephanie Wissel, T. Aune, Y. C. K. Chow, S. J. Fegan, D. Steele, V. A. Acciari, M. J. Lang, H. J. Rose, N. Karlsson, A. Cesarini, John L. Quinn, M. Bautista, K. G. Gibbs, Jamie Holder, L. C. Reyes, E. Roache, J. E. Ward, G. H. Gillanders, S. Godambe, M. McCutcheon, and OpenMETU
Subjects: Physics, nebula, 010308 nuclear & particles physics, ic-443, Molecular cloud, cosmic-rays, Flux, Astronomy and Astrophysics, Context (language use), xmm-newton observations, molecular clouds, Astrophysics, gamma-ray emission, 01 natural sciences, Pulsar wind nebula, ism: individual (ic 443=ver j0616.9+2230, = magic j0616+225), radiation, Space and Planetary Science, 0103 physical sciences, Supernova remnant, 010303 astronomy & astrophysics, gamma rays: observations, magic telescope, discovery, pulsar
Abstract: We present evidence that the very high energy (VHE, E > 100 GeV) gamma-ray emission coincident with the supernova remnant IC 443 is extended. IC 443 contains one of the best studied sites of supernova remnant/molecular cloud interaction and the pulsar wind nebula CXOU J061705.3+222127, both of which are important targets for VHE observations. VERITAS observed IC 443 for 37.9 hr during 2007 and detected emission above 300 GeV with an excess of 247 events, resulting in a significance of 8.3 standard deviations (sigma) before trials and 7.5 sigma after trials in a point-source search. The emission is centered at 6(h)16(m)51(s)+22 degrees 30'11 '' (J2000)+/- 0 degrees.03(stat)+/- 0 degrees.08(sys), with an intrinsic extension of 0 degrees.16 +/- 0 degrees.03(stat)+/- 0 degrees.04(sys). The VHE spectrum is well fit by a power law (dN/dE = N(0) x(E/TeV)(-Gamma)) with a photon index of 2.99 +/- 0.38(stat)+/- 0.3(sys) and an integral flux above 300 GeV of (4.63 +/- 0.90(stat)+/- 0.93(sys)) x 10(-12) cm(-2) s(-1). These results are discussed in the context of existing models for gamma-ray production in IC 443.
Published: 2009
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20. EVIDENCE FOR LONG-TERM GAMMA-RAY AND X-RAY VARIABILITY FROM THE UNIDENTIFIED TeV SOURCE HESS J0632+057

Author: V. A. Acciari, E. Aliu, T. Arlen, M. Beilicke, W. Benbow, D. Boltuch, S. M. Bradbury, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, Y. C. Chow, L. Ciupik, P. Cogan, R. Dickherber, C. Duke, T. Ergin, A. Falcone, S. J. Fegan, J. P. Finley, G. Finnegan, P. Fortin, L. Fortson, A. Furniss, K. Gibbs, G. H. Gillanders, J. Grube, R. Guenette, G. Gyuk, D. Hanna, J. Holder, D. Horan, C. M. Hui, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. J. Lang, S. LeBohec, G. Maier, A. McCann, M. McCutcheon, J. Millis, P. Moriarty, R. Mukherjee, R. A. Ong, A. N. Otte, D. Pandel, J. S. Perkins, D. Petry, M. Pohl, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, H. J. Rose, M. Schroedter, G. H. Sembroski, A. W. Smith, D. Steele, S. Swordy, M. Theiling, J. A. Toner, A. Varlotta, V. V. Vassiliev, S. Vincent, R. G. Wagner, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, T. Weisgarber, D. A. Williams, S. Wissel, and M. Wood
Subjects: stars, catalog, Be star, Astrophysics::High Energy Astrophysical Phenomena, binary, FOS: Physical sciences, Astrophysics, telescope, 01 natural sciences, emission, 0103 physical sciences, 010303 astronomy & astrophysics, acceleration of particles, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, stars: individual (hess j0632+057, mwc 148), Gamma ray, X-ray, Astronomy and Astrophysics, Crab Nebula, binaries: general, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, gamma rays: observations, discovery
Abstract: HESS J0632+057 is one of only two unidentified very-high-energy gamma-ray sources which appear to be point-like within experimental resolution. It is possibly associated with the massive Be star MWC 148 and has been suggested to resemble known TeV binary systems like LS I +61 303 or LS 5039. HESS J0632+057 was observed by VERITAS for 31 hours in 2006, 2008 and 2009. During these observations, no significant signal in gamma rays with energies above 1 TeV was detected from the direction of HESS J0632+057. A flux upper limit corresponding to 1.1% of the flux of the Crab Nebula has been derived from the VERITAS data. The non-detection by VERITAS excludes with a probability of 99.993% that HESS J0632+057 is a steady gamma-ray emitter. Contemporaneous X-ray observations with Swift XRT reveal a factor of 1.8+-0.4 higher flux in the 1-10 keV range than earlier X-ray observations of HESS J0632+057. The variability in the gamma-ray and X-ray fluxes supports interpretation of the ob ject as a gamma-ray emitting binary., Comment: 8 pages, 3 figures, Accepted for publication in The Astrophysical Journal
Published: 2009
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21. First results from VERITAS

Author: M. K. Daniel, F. Krennrich, A. Syson, L. Ciupik, S. P. Wakely, Abraham D. Falcone, F. Pizlo, G. H. Sembroski, Daniel Gall, R. A. Ong, H. Manseri, A. McCann, B. Zitzer, D. J. Fegan, S. J. Fegan, D. Steele, J. E. Ward, S. LeBohec, A. Cesarini, J. Hall, Y. C. K. Chow, S. M. Bradbury, Simon P. Swordy, M. Kertzman, John L. Quinn, D. Pandel, Martin Pohl, Henric Krawczynski, K. G. Gibbs, O. Celik, R. J. White, John Toner, J. S. Perkins, Yousaf M. Butt, V. V. Vassiliev, Pierre Colin, V. Bugaev, V. A. Acciari, S. B. Hughes, G. Blaylock, R. Guenette, G. H. Gillanders, Jacek Niemiec, H. M. Badran, R. G. Wagner, P. T. Reynolds, T. Nagai, P. A. Ogden, E. Hays, R. Amini, Geza Gyuk, O. J. Glidewell, D. Horan, Paul Dowkontt, Tulun Ergin, Reshmi Mukherjee, J. Millis, P. Moriarty, P. Fortin, H. J. Rose, Wei Cui, C. M. Hui, A. Konopelko, K. Lee, D. S. Hanna, L. Valcarcel, Lucy Fortson, Matthew Wood, C. Dowdall, M. McCutcheon, A. Imran, John Kildea, J. H. Buckley, M. J. Lang, J. P. Finley, C. Duke, A. W. Smith, E. Roache, T. C. Weekes, Stephanie Wissel, Amanda Weinstein, P. Cogan, Thomas Brian Humensky, K. Ragan, Karen Byrum, M. Schroedter, David Kieda, David A. Williams, J. Grube, Jamie Holder, G. E. Kenny, and P. Kaaret
Subjects: Physics, Nuclear and High Energy Physics, Active galactic nucleus, Sky, media_common.quotation_subject, Astronomy, Gamma-ray astronomy, Astrophysics, Blazar, Instrumentation, Galaxy, Cherenkov radiation, media_common
Abstract: VERITAS is an array of four, 12-m-diameter, Cherenkov telescopes, designed to explore the very-high-energy gamma-ray sky in the energy band between 100 GeV and 50 TeV. Its construction and commissioning have occurred over the past two years and the array has been taking scientific data with three or more telescopes since November 2006. We present results from observations made with VERITAS during the past observing season, including new results on the distant blazar 1ES 1218 + 304 , the active galaxy M87 and the high-mass X-ray binary system LS I + 61 303. We also describe the plans in place for the coming observing seasons.
Published: 2008
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22. The Whipple Observatory 10m gamma-ray telescope, 1997–2006

Author: G. E. Kenny, O. Celik, M. J. Lang, P. Moriarty, D. Petry, G. H. Gillanders, A. Konopelko, J. P. Finley, John Kildea, D. A. Carter-Lewis, F. Krennrich, T. C. Weekes, A. Syson, J. Millis, Y. C. K. Chow, J. Lloyd-Evans, I. D. Perez, I. Jung, M. K. Daniel, C. Duke, D. J. Fegan, H. J. Rose, R. J. White, S. P. Wakely, Daniel Gall, S. B. Hughes, J. S. Perkins, M. Jordan, A. W. Smith, J. Grube, Jamie Holder, J. H. Buckley, M. Schroedter, C. Dowdall, K. Gutierrez, John Toner, P. Cogan, S. M. Bradbury, G. H. Sembroski, R. W. Atkins, J. Knapp, P. A. Ogden, I. H. Bond, Henric Krawczynski, Lucy Fortson, R. A. Ong, D. Horan, S. LeBohec, J. Hall, T. Nagai, P. Rebillot, Martin Pohl, K. Kosack, Mark N. Quinn, Wei Cui, L. Valcarcel, M. Kertzman, G. Blaylock, H. M. Badran, V. V. Vassiliev, Tony Hall, Abraham D. Falcone, F. Pizlo, S. J. Fegan, and John L. Quinn
Subjects: Physics, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Context (language use), Gamma-ray astronomy, Cherenkov Telescope Array, law.invention, Primary mirror, Telescope, Observatory, law, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Cherenkov radiation, Fermi Gamma-ray Space Telescope
Abstract: Details are presented of the Whipple Observatory’s 10 m atmospheric Cherenkov telescope and camera, as it evolved during the period 1997 until 2006. The design of the telescope and camera’s optical and electronic systems is discussed together with a detailed description of the four-stage GRANITE (Gamma-RAy New Imaging TElescope) upgrade program, undertaken during the same time period. The objective of the upgrade was to improve the telescope’s sensitivity for the detection of very-high-energy gamma-rays. Results from the program are provided and are briefly discussed in the context of the design of VERITAS.
Published: 2007
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23. Status report from VERITAS

Author: Jamie Holder, I. Jung, M. J. Lang, Gernot Maier, S. P. Wakely, R. G. Wagner, D. A. Carter-Lewis, D. Steele, J. S. Perkins, P. Cogan, M. K. Daniel, Henric Krawczynski, David Kieda, E. Hays, John Kildea, Tulun Ergin, G. H. Gillanders, P. Kaaret, K G Gutierrez, A. J.R. Weinstein, Wei Cui, P Fortin, D. Horan, L. Valcarcel, G. E. Kenny, Thomas Brian Humensky, S. P. Swordy, C. Dowdall, David A. Williams, A. D. Falcone, S. J. Fegan, Karen Byrum, Stephanie Wissel, M. Schroedter, Lucy Fortson, S. M. Bradbury, V. V. Vassiliev, F. Pizlo, A. Konopelko, D. S. Hanna, A. Imran, John L. Quinn, G. H. Sembroski, K. G. Gibbs, H. J. Rose, J. H. Buckley, F. Krennrich, S. B. Hughes, Omer Celik, J. A. Toner, G. Blaylock, T. C. Weekes, T. Nagai, P. Moriarty, R. J. White, J. Grube, A. W. Smith, C. Duke, R. A. Ong, S. LeBohec, and J. Millis
Subjects: Physics, History, Observatory, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, High Energy Physics::Experiment, Astrophysics, Status report, Computer Science Applications, Education
Abstract: VERITAS is a ground-based gamma-ray observatory covering energies between 100 GeV and 50 TeV and will start operating by January 2007. We give a brief report of the construction status and performance characteristics of the telescopes.
Published: 2007
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24. Very High Energy Observations of Gamma‐Ray Burst Locations with the Whipple Telescope

Author: M. Schroedter, P. Cogan, J. Grube, R. W. Atkins, Vladimir Vassiliev, Y. C. K. Chow, M. K. Daniel, Karen Byrum, Gernot Maier, P. Fortin, A. D. Falcone, David Kieda, S. P. Wakely, John Kildea, H. Krawczynski, I. de la Calle Perez, Stephan LeBohec, S. P. Swordy, Jeremy Perkins, H. J. Rose, R. A. Ong, J. H. Buckley, R. J. White, K. Ragan, S. J. Fegan, D. Steele, P. T. Reynolds, M. Kertzman, M. J. Lang, Lucy Fortson, S. B. Hughes, R. G. Wagner, G. H. Sembroski, Thomas Brian Humensky, J. Hall, Jamie Holder, S. M. Bradbury, D. J. Fegan, P. Moriarty, John L. Quinn, G. Blaylock, J. P. Finley, T. C. Weekes, K. J. Gutierrez, D. Horan, T. N. Nagai, D. Petry, G. H. Gillanders, Frank Krennrich, C. Dowdall, O. Celik, D. S. Hanna, D. A. Williams, G. E. Kenny, H. M. Badran, John Toner, Wei Cui, L. Valcarcel, and Mark N. Quinn
Subjects: Physics, gamma rays : bursts, gamma rays : observations, Astronomy & Astrophysics, High energy, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics (astro-ph), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Afterglow, law.invention, Telescope, compton emission, refreshed shocks, external matter, light-curve, afterglows, tev, models, flares, discovery, search, Space and Planetary Science, Observatory, law, Spectral energy distribution, Blazar, Gamma-ray burst, Flare
Abstract: Gamma-ray burst (GRB) observations at very high energies (VHE, E > 100 GeV) can impose tight constraints on some GRB emission models. Many GRB afterglow models predict a VHE component similar to that seen in blazars and plerions, in which the GRB spectral energy distribution has a double-peaked shape extending into the VHE regime. VHE emission coincident with delayed X-ray flare emission has also been predicted. GRB follow-up observations have had high priority in the observing program at the Whipple 10m Gamma-ray Telescope and GRBs will continue to be high priority targets as the next generation observatory, VERITAS, comes on-line. Upper limits on the VHE emission, at late times (>~4 hours), from seven GRBs observed with the Whipple Telescope are reported here., Accepted for publication in the January 20, 2007 volume of the Astrophysical Journal, 655, 396
Published: 2007
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25. Introducing the CTA concept

Author: A. Mathieu, R. G. Wagner, K. Panagiotidis, S Rosier Lees, Julien Rousselle, M. Gómez Berisso, Michela Uslenghi, Stephen Maxfield, R. C. Shellard, Ivica Puljak, T. Le Flour, Thomas Schanz, Tobias C. Walther, Juanan Aguilar, Pierre Colin, M. Chikawa, N. Fouque, Mosè Mariotti, G. Fontaine, Merja Tornikoski, V. Diez-Blanco, Enrico Giro, A. Krepps, G. Koss, J. M. Martin, Sergio Billotta, E. de Oña Wilhelmi, Keitaro Takahashi, S. Buson, P. Brook, S. Steiner, M. Dyrda, Joseph Silk, Sera Markoff, P. Lubinski, U. Schwanke, Sauvik Bhattacharyya, J. Ripken, T. Haubold, C. Zurbach, H. Wetteskind, R. Hermel, J. Darling, J. Nicolau-Kukliński, Konstancja Satalecka, M. Videla, Stefan Funk, P. Conconi, S. Bajtlik, Lukasz Stawarz, J. M. Paredes, K. Reitberger, Stefan Wagner, Teresa Mineo, David Kieda, G. Pareschi, Shigeto Kabuki, Makoto Sawada, Antonio Stamerra, Rodolfo Canestrari, N. Baby, G. Crimi, P. Kostka, J. Grube, R. Zanin, I. K. Kominis, L. Mc Comb, R. Sternberger, M. Fesquet, M. Tokarz, David Fink, Daniela Dorner, N. Hamer Heras, A. Moralejo Olaizola, M. de Naurois, Diego F. Torres, Claes Fransson, K. Nishijima, Yutaka Fujita, L. Fresnillo, B. García, R. Kossakowski, A. Masserot, H. von Gunten, Alkiviadis F. Bais, Ciro Bigongiari, A. Saggion, G. Papyan, I. Mrusek, K. Farakos, J. Michałowski, A. Franckowiak, Fernando Martinez, M. Doert, R. Wawrzaszek, Michele Doro, L. Sapozhnikov, Claudia Lavalley, D. Thuermann, A.A. Zdziarski, Cristina Knapic, Karen Byrum, N. Neyroud, Petr Schovanek, W. Domainko, D. Kastana, E. Birsin, Adrian Biland, F. Sánchez, Alexandre Marcowith, M. Errando, R. L. C. Starling, J. Schultze, A. Weinstein, B. B. Singh, Yassir Moudden, Jelena Aleksić, C. L. Naumann, V. Waegebaert, M. Shayduk, U. F. Katz, Gianpiero Tagliaferri, M. Schroedter, A. Vollhardt, O. Reimann, Hideyuki Ohoka, Vincenzo Testa, C. Jablonski, Tsuguya Naito, J. Schäfer, Stavros Maltezos, A. Wierzcholska, P. Wawer, L. Nellen, F. Mirabel, Tatsuo Yoshida, P. H. Carton, Nina Nowak, L. Platos, Riccardo Rando, P. P. Krueger, R. Wischnewski, W. Romaszkan, E. Fede, Martino Marisaldi, Markus Gaug, Richard Willingale, J. H. Buckley, U. De AlmeidaBarres, J. Knapp, Saverio Lombardi, D. della Volpe, A. Herrero, A. Bottani, E. Delagnes, Martin J. Hardcastle, C. Morello, Anna Lipniacka, T. Greenshaw, M. Renaud, Giancarlo Cusumano, Jonathan Biteau, M. Sowiński, J. R. T. de Mello Neto, T. B. Humensky, Michael G. Richer, G. Parks, G. Grasseau, H. Baba, Gino Tosti, Damir Lelas, H. Krawzcynski, David Paneque, M. Barcelo, R. Dickherber, P. Ferrando, Shinji Hara, D. Florin, Hideaki Katagiri, T. Shibata, Fuyuki Tokanai, N. A. McCubbin, J. Gomez-Ortega, D. Nakajima, A. Liolios, P. Laporte, Orjan Dale, A. Sillanpää, Dainis Dravins, Timothée Grégoire, Nu. Komin, A. Mihailidis, L. Sidoli, Shiu-Hang Lee, A. W. Chen, J. M. Illa, A. Kuznetsov, P. Munar-Adrover, D. Dominis Prester, Marcos Daniel Actis, Abraham D. Falcone, L. Journet, D. Hadasch, N. Galante, A. Murphy, C. J. Todero Peixoto, S. Wiesand, A. Aravantinos, A. C. Rovero, J. L. Dournaux, P. Romano, M. Hrabovsky, R. de los Reyes Lopez, M. Ostrowski, J. Pallota, Geza Gyuk, Petar Temnikov, R. Dubois, Jan Ebr, R. Koul, David J. Smith, S. Schwarzburg, P. Manigot, Chad Finley, Tarek M. Hassan, Giuseppe Sottile, Evgeni Ovcharov, P. J. Rajda, F. Krennrich, Peter L. Moore, W. B. Focke, W. Bednarek, Elena Amato, Kazunori Kohri, J. Gamez-Garcia, I. Oya, A. Shibuya, German Hermann, William H. Lee, Dorota Sobczyńska, X. Zhou, C. Balkowski, G. Vallejo, M. Hayashida, M. Bitossi, Loukas Vlahos, H. Lockart, N. Geffroy, L. Tibaldo, Marek Jamrozy, Luke O'c. Drury, Pratik Majumdar, P. Sutcliffe, S. Schlenstedt, M. Palatka, Christophe Champion, H. Ueno, M. Rupiński, P. Giommi, J. Schwarz, G. Pühlhofer, Takashi Saito, W. van Driel, C. van Eldik, Q. Xiong, Yasuo Fukui, A. Donat, A. Ibarra, R. S. Warwick, Michiko Ohishi, A. W. Smith, J.-P. Lenain, Aion Viana, Terry Ashton, Guillaume Dubus, Jacek Niemiec, K. Kodani, Luis Ángel Tejedor, A. Wörnlein, Takanori Yoshikoshi, Masahiro Teshima, W. Gäbele, Ll. Font, Olaf Reimer, J. F. Valdés-Galicia, Lucy Fortson, J. P. Osborne, Mattia Fornasa, Keith Bechtol, Masayuki Tanaka, Shigehiro Nagataki, M. Rataj, M. Ribordy, Emmanuel Moulin, I. de la Calle, K. Winiarski, C. Jeanney, I. Mognet, I. Vegas, C. Juffroy, Yutaka Ohira, A. Jacholkowska, Matthew Wood, A. E. Suárez, J. Bähr, K. M. Schure, J. Maya, M. Dafonseca, J. Tasan, R. Sugawara, M. Bourgeat, A. Mancilla, D. Pelat, Olga Botner, D. Nedbal, G. Depaola, Robert Wagner, T. Okuda, H. Arnaldi, Josep Martí, P. Corona, T. Bonev, D. Yelos, J. Sieiro, V. Scalzotto, Jacco Vink, D. Languignon, Marco Ajello, J. Vandenbrouke, Philipp Mertsch, M. Mordalska, P. Wegner, P. Ziółkowski, P. T. O'Brien, A. Nozato, Robert D. Preece, B. Huber, Matteo Balbo, J.R. Bogart, R. Kankanyan, K. Mori, T. 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B., Kieda, T., Kifune, T., Kihm, T., Kishimoto, K., Kitamoto, W., Kluzniak, C., Knapic, J. w., Knapp, J., Knoedlseder, F., Koeck, J., Kocot, K., Kodani, J. . ., H., K., Kohri, K., Kokkota, D., Kolitzu, N., Komin, I., Komini, Y., Konno, H., Koeppel, P., Korohoda, K., Kosack, G., Ko, R., Kossakowski, P., Kostka, R., Koul, G., Kowal, S., Koyama, J., Koziol, T., Kraehenbuehl, J., Krause, H., Krawzcynski, F., Krennrich, A., Krepp, A., Kretzschmann, R., Krobot, P., Krueger, H., Kubo, V. A., Kudryavtsev, J., Kushida, A., Kuznetsov, A. L., Barbera, N. L., Palombara, V. L., Parola, G. L., Rosa, K., Lacombe, G., Lamanna, J., Lande, D., Languignon, J., Lapington, P., Laporte, C., Lavalley, T. L., Flour, A. L., Padellec, S. . ., H., W. H., Lee, M. A., Leigui, D., Lela, D. 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M., Comb, N., Mccubbin, I., Mchardy, R., Mckay, C., Medina, C., Melioli, D., Melkumyan, S., Mereghetti, P., Mertsch, M., Meucci, J., Michalowski, P., Micolon, A., Mihailidi, T., Mineo, M., Minuti, N., Mirabal, F., Mirabel, J. M., Miranda, R., Mirzoyan, T., Mizuno, B., Moal, R., Moderski, I., Mognet, E., Molinari, M., Molinaro, T., Montaruli, I., Monteiro, P., Moore, A. M., Olaizola, M., Mordalska, C., Morello, K., Mori, F., Mottez, Y., Moudden, E., Moulin, I., Mrusek, R., Mukherjee, P., Munar Adrover, H., Muraishi, K., Murase, A., Murphy, S., Nagataki, T., Naito, D., Nakajima, T., Nakamori, K., Nakayama, C., Naumann, D., Naumann, M., Naumann Godo, P., Nayman, D., Nedbal, D., Neise, L., Nellen, V., Neustroev, N., Neyroud, L., Nicastro, J., Nicolau Kuklinski, A., Niedzwiecki, J., Niemiec, D., Nieto, A., Nikolaidi, K., Nishijima, S., Nolan, R., Northrop, D., Nosek, N., Nowak, A., Nozato, P., O'Brien, Y., Ohira, M., Ohishi, S., Ohm, H., Ohoka, T., Okuda, A., Okumura, R. A., Ong, R., Orito, M., Orr, J., Osborne, M., Ostrowski, L. A., Otero, N., Otte, E., Ovcharov, I., Oya, A., Ozieblo, L., Padilla, S., Paiano, D., Paillot, A., Paizi, S., Palanque, M., Palatka, J., Pallota, K., Panagiotidi, D., Paneque, M., Panter, R., Paoletti, A., Papayanni, G., Papyan, J. M., Parede, G., Pareschi, G., Park, D., Parson, M. P., Arriba, M., Pech, G., Pedaletti, V., Pelassa, D., Pelat, M. D., C., M., Persic, P. . ., O., B., Peyaud, A., Pichel, S., Pita, F., Pizzolato, L., Plato, R., Platzer, L., Pogosyan, M., Pohl, G., Pojmanski, J. D., Ponz, W., Potter, J., Poutanen, E., Prandini, J., Prast, R., Preece, F., Profeti, H., Prokoph, M., Prouza, M., Proyetti, I., Puerto Gimenez, G., Puehlhofer, I., Puljak, M., Punch, R., Pyziol, E. J., Quel, J., Quinn, A., Quirrenbach, E., Racero, P. J., Rajda, P., Ramon, R., Rando, R. C., Rannot, M., Rataj, M., Raue, P., Reardon, O., Reimann, A., Reimer, O., Reimer, K., Reitberger, M., Renaud, S., Renner, B., Reville, W., Rhode, M., Ribo, M., Ribordy, M. G., Richer, J., Rico, J., Ridky, F., Rieger, P., Ringegni, J., Ripken, P. R., Ristori, A., Riviere, S., Rivoire, L., Rob, U., Roeser, R., Rohlf, G., Roja, P., Romano, W., Romaszkan, G. E., Romero, S., Rosen, S. R., Lee, D., Ro, G., Rouaix, J., Rousselle, S., Rousselle, A. C., Rovero, F., Roy, S., Royer, B., Rudak, C., Rulten, M., Rupinski, F., Russo, F., Ryde, B., Sacco, E. O., Saemann, A., Saggion, V., Safiakian, K., Saito, T., Saito, Y., Saito, N., Sakaki, R., Sakonaka, A., Salini, F., Sanchez, M., Sanchez Conde, A., Sandoval, H., Sandaker, E., Sant'Ambrogio, A., Santangelo, E. M., Santo, A., Sanuy, L., Sapozhnikov, S., Sarkar, N., Sartore, H., Sasaki, K., Satalecka, M., Sawada, V., Scalzotto, V., Scapin, M., Scarcioffolo, J., Schafer, T., Schanz, S., Schlenstedt, R., Schlickeiser, T., Schmidt, J., Schmoll, P., Schovanek, M., Schroedter, C., Schultz, J., Schultze, A., Schulz, K., Schure, T., Schwab, U., Schwanke, J., Schwarz, S., Schwarzburg, T., Schweizer, S., Schwemmer, A., Segreto, G. H., Sembroski, K., Seweryn, M., Sharma, M., Shayduk, R. C., Shellard, J., Shi, T., Shibata, A., Shibuya, E., Shum, L., Sidoli, M., Sidz, J., Sieiro, M., Sikora, J., Silk, A., Sillanpaa, B. B., Singh, J., Sitarek, C., Skole, R., Smareglia, A., Smith, D., Smith, J., Smith, N., Smith, D., Sobczynska, H., Sol, G., Sottile, M., Sowinski, F., Spanier, D., Spiga, S., Spyrou, V., Stamatescu, A., Stamerra, R., Starling, L., Stawarz, R., Steenkamp, C., Stegmann, S., Steiner, N., Stergioula, R., Sternberger, M., Sterzel, F., Stinzing, M., Stodulski, U., Straumann, E., Strazzeri, L., Stringhetti, A., Suarez, M., Suchenek, R., Sugawara, K. . ., H., S., Sun, A. D., Supanitsky, T., Suric, P., Sutcliffe, J., Syke, M., Szanecki, T., Szepieniec, A., Szostek, G., Tagliaferri, H., Tajima, H., Takahashi, K., Takahashi, L., Takalo, H., Takami, C., Talbot, J., Tammi, M., Tanaka, S., Tanaka, J., Tasan, M., Tavani, L. A., Tejedor, I., Telezhinsky, P., Temnikov, C., Tenzer, Y., Terada, R., Terrier, M., Teshima, V., Testa, D., Tezier, D., Thuermann, L., Tibaldo, O., Tibolla, A., Tiengo, M., Tluczykont, C. J., Todero, F., Tokanai, M., Tokarz, K., Toma, K., Torii, M., Tornikoski, D. F., Torre, M., Torre, G., Tosti, T., Totani, C., Toussenel, G., Tovmassian, P., Travnicek, M., Trifoglio, I., Troyano, K., Tsingano, H., Ueno, K., Umehara, S. S., Upadhya, T., Usher, M., Uslenghi, J. F., Valdes Galicia, P., Vallania, G., Vallejo, W. v., Driel, C. v., Eldik, J., Vandenbrouke, J., Vanderwalt, H., Vankov, G., Vasileiadi, V., Vassiliev, D., Veberic, I., Vega, S., Vercellone, S., Vergani, C., Veyssiere, J. P., Vialle, A., Viana, M., Videla, P., Vincent, S., Vincent, J., Vink, N., Vlahaki, L., Vlaho, P., Vogler, A., Vollhardt, H. . ., P., S., Vorobiov, C., Vuerli, V., Waegebaert, R., Wagner, R. G., Wagner, S., Wagner, S. P., Wakely, R., Walter, T., Walther, K., Warda, R., Warwick, P., Wawer, R., Wawrzaszek, N., Webb, P., Wegner, A., Weinstein, Q., Weitzel, R., Welsing, M., Werner, H., Wetteskind, R., White, A., Wierzcholska, S., Wiesand, M., Wilkinson, D. A., William, R., Willingale, K., Winiarski, R., Wischnewski, L., Wisniewski, M., Wood, A., Woernlein, Q., Xiong, K. K., Yadav, H., Yamamoto, T., Yamamoto, R., Yamazaki, S., Yanagita, J. M., Yebra, D., Yelo, A., Yoshida, T., Yoshida, T., Yoshikoshi, V., Zabalza, M., Zacharia, A., Zajczyk, R., Zanin, A., Zdziarski, A., Zech, A., Zhao, X., Zhou, K., Zietara, J., Ziolkowski, P., Ziolkowski, V., Zitelli, C., Zurbach, P., Zychowski, Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), APC - Astrophysique des Hautes Energies (APC - AHE), PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Università di Bologna [Bologna] (UNIBO)-Università di Bologna [Bologna] (UNIBO), Centre de Physique des Particules de Marseille (CPPM), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Aix Marseille Université (AMU), Institut de Recherches sur les lois Fondamentales de l'Univers (IRFU), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, CTA, Laboratoire Univers et Théories (LUTH (UMR_8102)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Galaxies, Etoiles, Physique, Instrumentation (GEPI), Laboratoire d'Annecy de Physique des Particules (LAPP), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Aix Marseille Université (AMU)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Dipartimento di Astronomia, Universita degli Studi di Bologna, Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO)-Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), and High Energy Astrophys. & Astropart. Phys (API, FNWI)
Subjects: Next generation Cherenkov telescopes, Ciencias Físicas, 01 natural sciences, 7. Clean energy, TeV GAMMA-RAY ASTRONOMY, Observatory, Air showers, HESS, Cherenkov Telescopes, 010303 astronomy & astrophysics, MISSION, SUPERNOVA REMNANT W44, TELESCOPE, ASTRONOMY, EMISSION, Physics, ta213, [SDU.ASTR.HE]Sciences of the Universe [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], Settore FIS/01 - Fisica Sperimentale, Astrophysics::Instrumentation and Methods for Astrophysics, TeV gamma-ray astronomy, ddc:540, CIENCIAS NATURALES Y EXACTAS, [PHYS.ASTR.HE]Physics [physics]/Astrophysics [astro-ph]/High Energy Astrophysical Phenomena [astro-ph.HE], [PHYS.ASTR.IM]Physics [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Air shower, AIR SHOWERS, Astrophysics::High Energy Astrophysical Phenomena, 0103 physical sciences, Preparatory phase, ta115, TeV gamma-ray astronomy Air showers Cherenkov Telescopes, 010308 nuclear & particles physics, business.industry, CHERENKOV TELESCOPES, Física, Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, ASTROFÍSICA, Cherenkov Telescope Array, [SDU.ASTR.IM]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Instrumentation and Methods for Astrophysic [astro-ph.IM], Astronomía, Design study, Telecommunications, business
Abstract: The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project., La lista completa de autores puede consultarse en el documento o en la página web de la revista., Facultad de Ingeniería
Published: 2013
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26. Erratum: VERITAS deep observations of the dwarf spheroidal galaxy Segue 1 [Phys. Rev. D85, 062001 (2012)]

Author: M. P. Connolly, D. Staszak, K. Ragan, R. Dickherber, S. Thibadeau, L. Ciupik, A. Varlotta, H. J. Rose, D. S. Hanna, T. C. Arlen, P. Kaaret, D. B. Saxon, E. Collins-Hughes, G. H. Sembroski, G. Hughes, Matthias Beilicke, A. McCann, A. Cesarini, M. Vivier, John L. Quinn, Francesc Ferrer, S. Archambault, Reshmi Mukherjee, K. Tsurusaki, Gernot Maier, Nahee Park, S. P. Wakely, C. Skole, A. Bouvier, Geza Gyuk, J. E. Ward, R. A. Ong, Thomas Weisgarber, Daniel Gall, E. Aliu, Matthew R. Orr, David Kieda, K. L. Byrum, Jodi Christiansen, J. S. Perkins, S. M. Bradbury, G. Tešić, David A. Williams, Lucy Fortson, A. Cannon, Pratik Majumdar, V. V. Vassiliev, T. Aune, I. Telezhinsky, Jamie Holder, S. Godambe, J. P. Dumm, J. Ruppel, Q. Feng, L. C. Reyes, Henric Krawczynski, Amy Furniss, A. J.R. Weinstein, T. B. Humensky, M. Schroedter, Wei Cui, S. McArthur, V. Bugaev, Wystan Benbow, F. Krennrich, G. Finnegan, A. W. Smith, M. Theiling, A. S Madhavan, A. D. Falcone, E. Roache, G. D. Şentürk, H. Huan, J. H. Buckley, P. Moriarty, Nicola Galante, J. Grube, R. G. Wagner, N. Karlsson, Sinéad M. Griffin, Y. Khassen, G. Decerprit, S. Vincent, M. Kertzman, A. N. Otte, P. T. Reynolds, B. Zitzer, Manel Errando, J. P. Finley, T. C. Weekes, M. Pohl, K. Lee, and H. Prokoph
Subjects: Physics, Gravitation, Nuclear and High Energy Physics, Dark matter, Gamma ray, Astronomy, Astrophysics, Segue, Cosmology, Dwarf galaxy, Dwarf spheroidal galaxy
Published: 2015
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27. Deployment of the VERITAS observatory

Author: S. P. Swordy, R. A. Ong, J. H. Buckley, M Schroedter, H. Manseri, Gernot Maier, F. Pizlo, S. LeBohec, D Horana, J. Lloyd-Evans, S. P. Wakely, G. Walker, Mark N. Quinn, G. Blaylock, J. Knapp, J. Hall, I. H. Bond, K. Ragan, H. M. Badran, F. Krennrich, R. W. Atkins, Vladimir Vassiliev, David Kieda, M. J. Lang, Martin Pohl, K. Kosack, P T Reynolds, Sm Bradbury, John L. Quinn, R. G. Wagner, D. Petry, K. G. Gibbs, Jeremy Perkins, S. Gammell, P Rebillot, E. Hays, P. A. Ogden, A. Syson, Reshmi Mukherjee, G. H. Gillanders, Jamie Holder, C Duke, Da Carter-Lewis, P. Fortin, H. J. Rose, D. J. Fegan, Y. C. Chow, G H Sembroski, Lucy Fortson, B. Power-Mooney, P. Moriarty, T Ergin, Dowdall, J. Grube, T. N. Nagai, A. D. Falcone, M K Daniel, M. A. Olevitch, David A. Williams, John Kildea, J. P. Finley, Henric Krawczynski, T. C. Weekes, R. J. White, S. B. Hughes, M. Kertzmann, Thomas Brian Humensky, P. Cogan, P. J. Boyle, S. J. Fegan, D. Steele, Paul Dowkontt, D. S. Hanna, W CuP, Jeffrey Zweerink, O. Celik, A. Milovanovic, G. E. Kenny, I. de la Calle Perez, P. Kaaret, E. Linton, and L. Valcarcel
Subjects: Physics, History, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Gamma ray, Radiation imaging, Astronomy, Cherenkov Telescope Array, Computer Science Applications, Education, law.invention, Telescope, Observatory, Software deployment, law, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Cherenkov radiation
Abstract: The Very Energetic Radiation Imaging Telescope Array System (VERITAS) being constructed in Southern Arizona consists of an array of four Atmospheric Cherenkov 12m Telescopes designed to observe astrophysical gamma rays in the energy range from 100 GeV to tens of TeV. A first telescope has been in operation on a temporary site since the end of 2004 and meets all specifications. The second is being installed on the same site, 85m from the first, in order to test stereoscopic capabilities. The full system of four telescopes is expected to be installed on the definitive site by the end of 2006.
Published: 2006
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28. Multiwavelength Observations of the Blazar Markarian 421 in 2002 December and 2003 January

Author: P. F. Rebillot, H. M. Badran, G. Blaylock, S. M. Bradbury, J. H. Buckley, D. A. Carter‐Lewis, O. Celik, Y. C. Chow, P. Cogan, W. Cui, M. Daniel, C. Duke, A. Falcone, S. J. Fegan, J. P. Finley, L. F. Fortson, G. H. Gillanders, J. Grube, K. Gutierrez, G. Gyuk, D. Hanna, J. Holder, D. Horan, S. B. Hughes, G. E. Kenny, M. Kertzman, D. Kieda, J. Kildea, K. Kosack, H. Krawczynski, F. Krennrich, M. J. Lang, S. Le Bohec, E. Linton, G. Maier, P. Moriarty, J. Perkins, M. Pohl, J. Quinn, K. Ragan, P. T. Reynolds, H. J. Rose, M. Schroedter, G. H. Sembroski, G. Steele, S. P. Swordy, L. Valcarcel, V. V. Vassiliev, S. P. Wakely, T. C. Weekes, J. Zweerink, (The VERITAS Collaboration), M. Aller, H. Aller, P. Boltwood, I. Jung, D. Kranich, K. Nilsson, M. Pasanen, A. Sadun, and A. Sillanpaa
Subjects: tev gamma-rays, Astrophysics::High Energy Astrophysical Phenomena, media_common.quotation_subject, bl-lacertae objects, bl lacertae objects : individual (mrk 421), Astrophysics, 01 natural sciences, Radio spectrum, law.invention, law, spectral evolution, Target of opportunity, 0103 physical sciences, strong flares, crab-nebula, 010306 general physics, Blazar, 010303 astronomy & astrophysics, media_common, mechanisms : nonthermal, Physics, HEGRA, Astronomy and Astrophysics, lac objects, Light curve, galaxies : jets, mkn 501, Crab Nebula, x-ray, Space and Planetary Science, Sky, active galactic nuclei, gamma rays : observations radiation, self-compton model, x-rays : individual (mrk 421), Flare
Abstract: We report on a multiwavelength campaign on the TeV gamma-ray blazar Mrk 421 performed during 2002 December and 2003 January. These target of opportunity observations were initiated by the detection of X-ray and TeV gamma-ray flares with the All Sky Monitor (ASM) on board the Rossi X-Ray Timing Explorer (RXTE) and the 10 m Whipple gamma-ray telescope. The campaign included observational coverage in the radio (University of Michigan Radio Astronomy Observatory), optical (Boltwood, La Palma KVA 0.6 m; WIYN 0.9 m), X-ray (RXTE pointed telescopes), and TeV gamma-ray (Whipple and HEGRA) bands. At TeV energies, the observations revealed several flares at intermediate flux levels, peaking between 1 and 1.5 times the flux from the Crab Nebula. While the time-averaged spectrum can be fitted with a single power law of photon index Gamma = 2.8 from dN gamma/dE proportional to E-Gamma, we find some evidence for spectral variability. Confirming earlier results, the campaign reveals a rather loose correlation between the X-ray and TeV gamma-ray fluxes. In one case, a very strong X-ray flare is not accompanied by a comparable TeV gamma-ray flare. Although the source flux was variable in the optical and radio bands, the sparse sampling of the optical and radio light curves does not allow us to study the correlation properties in detail. We present a simple analysis of the data with a synchrotron self-Compton model, emphasizing that models with very high Doppler factors and low magnetic fields can describe the data.
Published: 2006
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29. Upper Limits on the Extragalactic Background Light from the Very High Energy Gamma‐Ray Spectra of Blazars

Author: M. Schroedter
Subjects: Physics, Spectral index, Photon, Infrared, Astrophysics::High Energy Astrophysical Phenomena, Gamma ray, Computer Science::Computation and Language (Computational Linguistics and Natural Language and Speech Processing), Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Spectral line, Redshift, Extragalactic background light, Space and Planetary Science, Blazar
Abstract: The direct measurement of the extragalactic background light (EBL) is difficult at optical to infrared wavelengths because of the strong foreground radiation originating in the Solar System. Very high energy (VHE, E$>$100 GeV) gamma rays interact with EBL photons of these wavelengths through pair production. In this work, the available VHE spectra from six blazars are used to place upper limits on the EBL. These blazars have been detected over a range of redshifts and a steepening of the spectral index is observed with increasing source distance. This can be interpreted as absorption by the EBL. In general, knowledge of the intrinsic source spectrum is necessary to determine the density of the intervening EBL. Motivated by the observed spectral steepening with redshift, upper limits on the EBL are derived by assuming that the intrinsic spectra of the six blazars are $\propto E^{-1.8}$. Upper limits are then placed on the EBL flux at discrete energies without assuming a specific spectral shape for the EBL. This is an advantage over other methods since the EBL spectrum is uncertain.
Published: 2005
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30. A Survey of Unidentified EGRET Sources at Very High Energies

Author: J. McEnery, A. M. Hillas, O. Celik, J. H. Buckley, C. Duke, J. Grube, A. Syson, Dietrich Müller, David Kieda, J. Lloyd-Evans, A. Jarvis, J. Hall, K. Ragan, Reshmi Mukherjee, K. Kosack, P. Moriarty, F. Krennrich, V. V. Vassiliev, M. K. Daniel, G. H. Sembroski, J. Knapp, Wei Cui, B. Power-Mooney, D. J. Fegan, S. P. Swordy, Jamie Holder, I. de la Calle Perez, P. T. Reynolds, S. P. Wakely, G. Walker, S. J. Fegan, R. A. Ong, S. Le Bohec, G. E. Kenny, I. H. Bond, M. Schroedter, J. P. Finley, R. Pallassini, T. C. Weekes, Lucy Fortson, M. Jordan, M. Catanese, D. Petry, John Kildea, D. S. Hanna, P. Rebillot, P. J. Boyle, E. Linton, Henric Krawczynski, D. A. Carter-Lewis, H. M. Badran, M. D'Vali, Tony Hall, Mark N. Quinn, M. J. Lang, J. A. Gaidos, S. J. Nolan, A. Milovanovic, R. W. Lessard, Jeffrey Zweerink, H. J. Rose, S. M. Bradbury, Abraham D. Falcone, M. Kertzman, D. Horan, John L. Quinn, K. G. Gibbs, S. Gammell, T. N. Nagai, and G. H. Gillanders
Subjects: tev energies, Astrophysics::High Energy Astrophysical Phenomena, sax j0635+0533, Flux, error box, Astrophysics, galactic plane, law.invention, Telescope, surveys, supernova-remnants, galaxies : jets, gamma rays : observations, gamma-ray sources, source 3eg j2227+6122, x-ray, ls i+61-degrees-303, galaxy clusters, Observatory, law, Egret, Astrophysics::Galaxy Astrophysics, Galaxy cluster, Physics, biology, Astronomy, Astronomy and Astrophysics, Galactic plane, biology.organism_classification, Galaxy, Space and Planetary Science
Abstract: The Whipple Observatory 10 m γ-ray telescope has been used to survey the error boxes of EGRET unidentified sources in an attempt to find counterparts at energies of 350 GeV and above. Twenty-one unidentified sources detected by EGRET (more than 10% of the total number) have been included in this survey. In no case is a statistically significant signal found in the EGRET error box, which implies that, at least for this sample, the γ-ray spectra of these sources steepen between 100 MeV and 350 GeV. For each EGRET source location, we list candidate associations and derive upper limits on the integral γ-ray flux above 350 GeV.
Published: 2005
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31. Spectrum of Very High Energy Gamma‐Rays from the blazar 1ES 1959+650 during Flaring Activity in 2002

Author: M. K. Daniel, H. M. Badran, I. H. Bond, P. J. Boyle, S. M. Bradbury, J. H. Buckley, D. A. Carter‐Lewis, M. Catanese, O. Celik, P. Cogan, W. Cui, M. D’Vali, I. de la Calle Perez, C. Duke, A. Falcone, D. J. Fegan, S. J. Fegan, J. P. Finley, L. F. Fortson, J. A. Gaidos, S. Gammell, K. Gibbs, G. H. Gillanders, J. Grube, J. Hall, T. A. Hall, D. Hanna, A. M. Hillas, J. Holder, D. Horan, T. B. Humensky, A. Jarvis, M. Jordan, G. E. Kenny, M. Kertzman, D. Kieda, J. Kildea, J. Knapp, K. Kosack, H. Krawczynski, F. Krennrich, M. J. Lang, S. Le Bohec, E. Linton, J. Lloyd‐Evans, A. Milovanovic, P. Moriarty, D. Muller, T. Nagai, S. Nolan, R. A. Ong, R. Pallassini, D. Petry, B. Power‐Mooney, J. Quinn, M. Quinn, K. Ragan, P. Rebillot, P. T. Reynolds, H. J. Rose, M. Schroedter, G. H. Sembroski, S. P. Swordy, A. Syson, V. V. Vassiliev, S. P. Wakely, G. Walker, T. C. Weekes, and J. Zweerink
Subjects: tev energies, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Astrophysics, system, techniques : spectroscopic, law.invention, Telescope, project, law, Coincident, bl lacertae objects : individual (1es 1959+650), gamma rays : observations, strong flares, Blazar, Cherenkov radiation, Physics, Spectral index, Range (particle radiation), Astrophysics (astro-ph), Gamma ray, h1426+428, Astronomy and Astrophysics, calibration, radiation, Space and Planetary Science, cherenkov telescopes, markarian-421, High Energy Physics::Experiment, Flare
Abstract: The blazar 1ES 1959+650 was observed in a flaring state with the Whipple 10 m Imaging Atmospheric Cherenkov Telescope during May of 2002. A spectral analysis has been carried out on the data from that time period and the resulting very high energy gamma-ray spectrum ($E \geq 316$ GeV) can be well fit by a power-law of differential spectral index \alpha = 2.78 +/- 0.12_{stat.} +/- 0.21_{sys.}. On June 4th 2002, the source flared dramatically in the gamma-ray range without any coincident increase in the X-ray emission, providing the first unambiguous example of an `orphan' gamma-ray flare from a blazar. The gamma-ray spectrum for these data can also be described by a simple power-law fit with \alpha = 2.82 +/- 0.15_{stat.} +/- 0.30_{sys.}. There is no compelling evidence for spectral variability, or for any cut-off to the spectrum., Comment: 25 pages. Collaboration website at http://veritas.sao.arizona.edu/
Published: 2005
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32. VERITAS: the Very Energetic Radiation Imaging Telescope Array System

Author: M. K. Daniel, S. P. Wakely, G. Walker, John Kildea, J. H. Buckley, David Kieda, Mark N. Quinn, A. Jarvis, S. M. Bradbury, S. P. Swordy, A. Milovanovic, Wei Cui, A. Syson, D. Horan, F. Krennrich, M. Schroedter, V. V. Vassiliev, Abraham D. Falcone, G. E. Kenny, H. J. Rose, R. Pallassini, Lucy Fortson, P. J. Boyle, E. Linton, D. S. Hanna, J. A. Gaidos, M. D'Vali, P. Moriarty, S. J. Nolan, M. Jordan, Jeffrey Zweerink, J. Hall, K. Ragan, Tony Hall, J. Knapp, K. Kosack, D. A. Carter-Lewis, D. Petry, J. Lloyd-Evans, Dietrich Müller, G. H. Gillanders, B. Power-Mooney, G. H. Sembroski, Jamie Holder, S. LeBohec, I. de la Calle Perez, I. H. Bond, M. J. Lang, S. J. Fegan, Henric Krawczynski, M. Kertzman, T. N. Nagai, J. Grube, P. Rebillot, P. T. Reynolds, J. P. Finley, C. Duke, T. C. Weekes, D. J. Fegan, John L. Quinn, K. G. Gibbs, R. A. Ong, S. Gammell, A. M. Hillas, and O. Celik
Subjects: Physics, tev energies, Astrophysics::High Energy Astrophysical Phenomena, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy, Astronomy and Astrophysics, Gamma-ray astronomy, Astrophysics, First light, Cherenkov Telescope Array, law.invention, Telescope, Primary mirror, Space and Planetary Science, law, Observatory, gamma-ray astronomy, atmospheric cherenkov detectors, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Astrophysics::Galaxy Astrophysics, Very Energetic, Cherenkov radiation
Abstract: The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is the major next generation imaging atmospheric Cherenkov γ-ray telescope in the western hemisphere and will be located in southern Arizona nearby Kitt Peak National Observatory. The VERITAS observatory will provide unprecedented sensitivity to photon energies between 50 GeV and 50 TeV. The first stage is an array of four telescopes to be fully operational in early 2006, with an expansion to seven telescopes envisioned for 2008. The construction of a prototype telescope is underway, for which first light is expected in Fall 2003. The technical concept is outlined and a progress report is given.
Published: 2004
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33. Determination of land surface temperature distributions from single channel IR measurements: An effective spatial interpolation method for the use of TOVS, ECMWF and radiosonde profiles in the atmospheric correction scheme

Author: H. Fischer, F. Olesen, and M. Schroedter
Subjects: Meteorology, Advanced very-high-resolution radiometer, Atmospheric correction, Sampling (statistics), Physics::Geophysics, law.invention, Multivariate interpolation, law, Brightness temperature, Radiosonde, TOVS, General Earth and Planetary Sciences, Radiometry, Environmental science, ATOVS, atmospheric correction, spatial interpolation, Physics::Atmospheric and Oceanic Physics, Remote sensing, Interpolation
Abstract: For the determination of land surface temperatures from brightness temperature measurements in a single infrared channel, as for instance taken by the Advanced Very High Resolution Radiometer (AVHRR) or Meteosat, an explicit correction of the atmospheric influence is necessary. Therefore, the vertical and horizontal distribution of temperature and humidity has to be known. Possible sources for these atmospheric profiles are TOVS measurements, the ECMWF analysis and radiosonde data. These sources provide the information discretely in space and time and are particularly characterized by large differences in horizontal resolution. This paper presents a method that overcomes the problems arising from the different spatial sampling. Furthermore, some case studies with AVHRR infrared measurements will be presented and atmospheric corrections based on TOVS, ECMWF and radiosonde profiles will be intercompared.
Published: 2003
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34. The TeV Spectrum of H1426+428

Author: Vladimir Vassiliev, Dietrich Müller, Jamie Holder, S. M. Bradbury, Frank Krennrich, M. Kertzman, S. J. Fegan, A. M. Hillas, T. N. Nagai, John Kildea, D. J. Fegan, D. Horan, Wei Cui, M. Schroedter, J. Hall, S. Gammell, J. P. Finley, K. Kosack, J. Knapp, C. Duke, D. A. Carter-Lewis, T. C. Weekes, S. P. Swordy, R. A. Ong, Morgan T. Page, R. Sidwell, P. Moriarty, I. H. Bond, S. P. Wakely, S. LeBohec, N. Stanton, B. Power-Mooney, G. Walker, I. de la Calle Perez, D. Petry, Tony Hall, J. H. Buckley, J. A. Gaidos, David Kieda, G. H. Sembroski, R. Pallassini, M. Jordan, Abraham D. Falcone, H. J. Rose, N. W. Reay, John L. Quinn, K. G. Gibbs, and P. T. Reynolds
Subjects: Normalization (statistics), Physics, ray, Astrophysics::High Energy Astrophysical Phenomena, Spectrum (functional analysis), Flux, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Space (mathematics), Power law, objects, Crab Nebula, Space and Planetary Science, bl lacertae objects : individual (h1426+428), gamma rays : observations, High Energy Physics::Experiment, Blazar, BL Lac object
Abstract: The BL Lac object H1426+428 was recently detected as a high energy gamma-ray source by the VERITAS collaboration (Horan et al. 2002). We have reanalyzed the 2001 portion of the data used in the detection in order to examine the spectrum of H1426+428 above 250 GeV. We find that the time-averaged spectrum agrees with a power law of the shape dF/dE = 10^(-7.31 +- 0.15(stat) +- 0.16(syst)) x E^(-3.50 +- 0.35(stat) +- 0.05(syst)) m^(-2)s^(-1)TeV^(-1) The statistical evidence from our data for emission above 2.5 TeV is 2.6 sigma. With 95% c.l., the integral flux of H1426+428 above 2.5 TeV is larger than 3% of the corresponding flux from the Crab Nebula. The spectrum is consistent with the (non-contemporaneous) measurement by Aharonian et al. (2002) both in shape and in normalization. Below 800 GeV, the data clearly favours a spectrum steeper than that of any other TeV Blazar observed so far indicating a difference in the processes involved either at the source or in the intervening space., Comment: LaTeX, 8 pages, 4 figures, accepted for publication in ApJ
Published: 2002
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35. THE JUNE 2008 FLARE OF MARKARIAN 421 FROM OPTICAL TO TeV ENERGIES

Author: I. Donnarumma, V. Vittorini, S. Vercellone, E. Del Monte, M. Feroci, F. D'Ammando, L. Pacciani, A. W. Chen, M. Tavani, A. Bulgarelli, A. Giuliani, F. Longo, G. Pucella, A. Argan, G. Barbiellini, F. Boffelli, P. Caraveo, P. W. Cattaneo, V. Cocco, E. Costa, G. De Paris, G. Di Cocco, Y. Evangelista, M. Fiorini, T. Froysland, M. Frutti, F. Fuschino, M. Galli, F. Gianotti, C. Labanti, I. Lapshov, F. Lazzarotto, P. Lipari, M. Marisaldi, M. Mastropietro, S. Mereghetti, E. Morelli, A. Morselli, A. Pellizzoni, F. Perotti, P. Picozza, G. Porrovecchio, M. Prest, M. Rapisarda, A. Rappoldi, A. Rubini, P. Soffitta, M. Trifoglio, A. Trois, E. Vallazza, A. Zambra, D. Zanello, C. Pittori, P. Santolamazza, F. Verrecchia, P. Giommi, S. Colafrancesco, L. Salotti, M. Villata, C. M. Raiteri, W. P. Chen, N. V. Efimova, B. Jordan, T. S. Konstantinova, E. Koptelova, O. M. Kurtanidze, V. M. Larionov, J. A. Ros, A. C. Sadun, H. Anderhub, L. A. Antonelli, P. Antoranz, M. Backes, C. Baixeras, S. Balestra, J. A. Barrio, H. Bartko, D. Bastieri, J. Becerra González, J. K. Becker, W. Bednarek, K. Berger, E. Bernardini, A. Biland, R. K. Bock, G. Bonnoli, P. Bordas, D. Borla Tridon, V. Bosch-Ramon, T. Bretz, I. Britvitch, M. Camara, E. Carmona, A. Chilingarian, S. Commichau, J. L. Contreras, J. Cortina, M. T. Costado, S. Covino, V. Curtef, F. Dazzi, A. De Angelis, E. De Cea del Pozo, R. de los Reyes, B. De Lotto, M. De Maria, F. De Sabata, C. Delgado Mendez, A. Dominguez, D. Dorner, M. Doro, D. Elsaesser, M. Errando, D. Ferenc, E. Fernández, R. Firpo, M. V. Fonseca, L. Font, N. Galante, R. J. García López, M. Garczarczyk, M. Gaug, F. Goebel, D. Hadasch, M. Hayashida, A. Herrero, D. Höhne-Mönch, J. Hose, C. C. Hsu, S. Huber, T. Jogler, D. Kranich, A. La Barbera, A. Laille, E. Leonardo, E. Lindfors, S. Lombardi, M. López, E. Lorenz, P. Majumdar, G. Maneva, N. Mankuzhiyil, K. Mannheim, L. Maraschi, M. Mariotti, M. Martínez, D. Mazin, M. Meucci, M. Meyer, J. M. Miranda, R. Mirzoyan, J. Moldón, M. Moles, A. Moralejo, D. Nieto, K. Nilsson, J. Ninkovic, I. Oya, R. Paoletti, J. M. Paredes, M. Pasanen, D. Pascoli, F. Pauss, R. G. Pegna, M. A. Perez-Torres, M. Persic, L. Peruzzo, F. Prada, E. Prandini, N. Puchades, A. Raymers, W. Rhode, M. Ribó, J. Rico, M. Rissi, A. Robert, S. Rügamer, A. Saggion, T. Y. Saito, M. Salvati, M. Sanchez-Conde, P. Sartori, K. Satalecka, V. Scalzotto, V. Scapin, T. Schweizer, M. Shayduk, K. Shinozaki, S. N. Shore, N. Sidro, A. Sierpowska-Bartosik, A. Sillanpää, J. Sitarek, D. Sobczynska, F. Spanier, A. Stamerra, L. S. Stark, L. Takalo, F. Tavecchio, P. Temnikov, D. Tescaro, M. Teshima, M. Tluczykont, D. F. Torres, N. Turini, H. Vankov, A. Venturini, V. Vitale, R. M. Wagner, W. Wittek, V. Zabalza, F. Zandanel, R. Zanin, J. Zapatero, V. Acciari, E. Aliu, T. Arlen, M. Beilicke, W. Benbow, S. M. Bradbury, J. H. Buckley, V. Bugaev, Y. Butt, K. Byrum, A. Cannon, A. Cesarini, Y. C. Chow, L. Ciupik, P. Cogan, P. Colin, W. Cui, M. K. Daniel, R. Dickherber, C. Duke, T. Ergin, S. J. Fegan, J. P. Finley, G. Finnegan, P. Fortin, A. Furniss, D. Gall, G. H. Gillanders, R. Guenette, G. Gyuk, J. Grube, D. Hanna, J. Holder, D. Horan, C. M. Hui, T. Brian Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, D. Kieda, J. Kildea, A. Konopelko, H. Krawczynski, F. Krennrich, M. J. Lang, S. LeBohec, G. Maier, A. McCann, M. McCutcheon, A. Milovanovic, P. Moriarty, T. Nagai, R. A. Ong, A. N. Otte, D. Pandel, J. S. Perkins, A. Pichel, M. Pohl, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, H. J. Rose, M. Schroedter, G. H. Sembroski, A. W. Smith, D. Steele, S. P. Swordy, M. Theiling, J. A. Toner, L. Valcarcel, A. Varlotta, S. P. Wakely, J. E. Ward, T. C. Weekes, A. Weinstein, D. A. Williams, S. Wissel, M. Wood, B. Zitzer, I., Donnarumma, V., Vittorini, S., Vercellone, E. D., Monte, M., Feroci, F., D'Ammando, L., Pacciani, A. W., Chen, M., Tavani, A., Bulgarelli, A., Giuliani, Longo, Francesco, G., Pucella, A., Argan, G., Barbiellini, F., Boffelli, P., Caraveo, P. W., Cattaneo, V., Cocco, E., Costa, G. D., Pari, G. D., Cocco, Y., Evangelista, M., Fiorini, T., Froysland, M., Frutti, F., Fuschino, M., Galli, F., Gianotti, C., Labanti, I., Lapshov, F., Lazzarotto, P., Lipari, M., Marisaldi, M., Mastropietro, S., Mereghetti, E., Morelli, A., Morselli, A., Pellizzoni, F., Perotti, P., Picozza, G., Porrovecchio, M., Prest, M., Rapisarda, A., Rappoldi, A., Rubini, P., Soffitta, M., Trifoglio, A., Troi, E., Vallazza, A., Zambra, D., Zanello, C., Pittori, P., Santolamazza, F., Verrecchia, P., Giommi, S., Colafrancesco, L., Salotti, M., Villata, C. M., Raiteri, W. P., Chen, N. V., Efimova, B., Jordan, T. S., Konstantinova, E., Koptelova, O. M., Kurtanidze, V. M., Larionov, J. A., Ro, A. C., Sadun, H., Anderhub, L. A., Antonelli, P., Antoranz, M., Backe, C., Baixera, S., Balestra, J. A., Barrio, H., Bartko, D., Bastieri, J. B., Gonzalez, J. K., Becker, W., Bednarek, K., Berger, E., Bernardini, A., Biland, R. K., Bock, G., Bonnoli, P., Borda, D. B., Tridon, V., Bosch Ramon, T., Bretz, I., Britvitch, M., Camara, E., Carmona, A., Chilingarian, S., Commichau, J. L., Contrera, J., Cortina, M. T., Costado, S., Covino, V., Curtef, F., Dazzi, A. D., Angeli, E. D., Del Pozo, R. D., Reye, B. D., Lotto, M. D., Maria, F. D., Sabata, C. D., Mendez, A., Dominguez, D., Dorner, M., Doro, D., Elsaesser, M., Errando, D., Ferenc, E., Fernandez, R., Firpo, M. V., Fonseca, L., Font, N., Galante, R. J. G., Lopez, M., Garczarczyk, M., Gaug, F., Goebel, D., Hadasch, M., Hayashida, A., Herrero, D., Hohne Monch, J., Hose, C. C., Hsu, S., Huber, T., Jogler, D., Kranich, A. L., Barbera, A., Laille, E., Leonardo, E., Lindfor, S., Lombardi, M., Lopez, E., Lorenz, P., Majumdar, G., Maneva, N., Mankuzhiyil, K., Mannheim, L., Maraschi, M., Mariotti, M., Martinez, D., Mazin, M., Meucci, M., Meyer, J. M., Miranda, R., Mirzoyan, J., Moldon, M., Mole, A., Moralejo, D., Nieto, K., Nilsson, J., Ninkovic, I., Oya, R., Paoletti, J. M., Parede, M., Pasanen, D., Pascoli, F., Pau, R. G., Pegna, M. A., Perez Torre, M., Persic, L., Peruzzo, F., Prada, E., Prandini, N., Puchade, A., Raymer, W., Rhode, M., Ribo, J., Rico, M., Rissi, A., Robert, S., Rugamer, A., Saggion, T. Y., Saito, M., Salvati, M., Sanchez Conde, P., Sartori, K., Satalecka, V., Scalzotto, V., Scapin, T., Schweizer, M., Shayduk, K., Shinozaki, S. N., Shore, N., Sidro, A., Sierpowska Bartosik, A., Sillanpaa, J., Sitarek, D., Sobczynska, F., Spanier, A., Stamerra, L. S., Stark, L., Takalo, F., Tavecchio, P., Temnikov, D., Tescaro, M., Teshima, M., Tluczykont, D. F., Torre, N., Turini, H., Vankov, A., Venturini, V., Vitale, R. M., Wagner, W., Wittek, V., Zabalza, F., Zandanel, R., Zanin, J., Zapatero, V., Acciari, E., Aliu, T., Arlen, M., Beilicke, W., Benbow, S. M., Bradbury, J. H., Buckley, V., Bugaev, Y., Butt, K., Byrum, A., Cannon, A., Cesarini, Y. C., Chow, L., Ciupik, P., Cogan, P., Colin, W., Cui, M. K., Daniel, R., Dickherber, C., Duke, T., Ergin, S. J., Fegan, J. P., Finley, G., Finnegan, P., Fortin, A., Furni, D., Gall, G. H., Gillander, R., Guenette, G., Gyuk, J., Grube, D., Hanna, J., Holder, D., Horan, C. M., Hui, T. B., Humensky, A., Imran, P., Kaaret, N., Karlsson, M., Kertzman, D., Kieda, J., Kildea, A., Konopelko, H., Krawczynski, F., Krennrich, M. J., Lang, S., Lebohec, G., Maier, A., Mccann, M., Mccutcheon, A., Milovanovic, P., Moriarty, T., Nagai, R. A., Ong, A. N., Otte, D., Pandel, J. S., Perkin, A., Pichel, M., Pohl, K., Ragan, L. C., Reye, P. T., Reynold, E., Roache, H. J., Rose, M., Schroedter, G. H., Sembroski, A. W., Smith, D., Steele, S. P., Swordy, M., Theiling, J. A., Toner, L., Valcarcel, A., Varlotta, S. P., Wakely, J. E., Ward, T. C., Weeke, A., Weinstein, D. A., William, S., Wissel, M., Wood, B., Zitzer, Donnarumma I, Vittorini V, Vercellone S, del Monte E, Feroci M, DAmmando F, Pacciani L, Chen A W, Tavani M, Bulgarelli A, Giuliani A, Longo F, Pucella G, Argan A, Barbiellini G, Boffelli F, Caraveo P, Cattaneo P W, Cocco V, Costa E, DeParis G, Di Cocco G, Evangelista Y, Fiorini M, Froysland T, Frutti M, Fuschino F, Galli M, Gianotti F, Labanti C, Lapshov I, Lazzarotto F, Lipari P, Marisaldi M, Mastropietro M, Mereghetti S, Morelli E, Morselli A, Pellizzoni A, Perotti F, Picozza P, Porrovecchio G, Prest M, Rapisarda M, Rappoldi A, Rubini A, Soffitta P, Trifoglio M, Trois A, Vallazza E, Zambra A, Zanello D, Pittori C, Santolamazza P, Verrecchia F, Giommi P, Colafrancesco S, Salotti L, Villata M, Raiteri C M, Chen W P, Efimova N V, Jordan B, Konstantinova T S, Koptelova E, Kurtanidze O M, Larionov V M, Ros J A, Sadun A C, Anderhub H, Antonelli L A, Antoranz P, Backes M, Baixeras C, Balestra S, Barrio J A, Bartko H, Bastieri D, González J Becerra, Becker J K, Bednarek W, Berger K, Bernardini E, Biland A, Bock R K, Bonnoli G, Bordas P, Tridon D Borla, Bosch-Ramon V, Bretz T, Britvitch I, Camara M, Carmona E, Chilingarian A, Commichau S, Contreras J L, Cortina J, Costado M T, Covino S, Curtef V, Dazzi F, DeAngelis A, DeCea del Pozo E, de los Reyes R, DeLotto B, DeMaria M, DeSabata F, Mendez C Delgado, Dominguez A, Dorner D, Doro M, Elsaesser D, Errando M, Ferenc D, Fernández E, Firpo R, Fonseca M V, Font L, Galante N, García López R J, Garczarczyk M, Gaug M, Goebel F, Hadasch D, Hayashida M, Herrero A, Höhne-Mönch D, Hose J, Hsu C C, Huber S, Jogler T, Kranich D, La Barbera A, Laille A, Leonardo E, Lindfors E, Lombardi S, López M, Lorenz E, Majumdar P, Maneva G, Mankuzhiyil N, Mannheim K, Maraschi L, Mariotti M, Martínez M, Mazin D, Meucci M, Meyer M, Miranda J M, Mirzoyan R, Moldón J, Moles M, Moralejo A, Nieto D, Nilsson K, Ninkovic J, Oya I, Paoletti R, Paredes J M, Pasanen M, Pascoli D, Pauss F, Pegna R G, Perez-Torres M A, Persic M, Peruzzo L, Prada F, Prandini E, Puchades N, Raymers A, Rhode W, Ribó M, Rico J, Rissi M, Robert A, Rügamer S, Saggion A, Saito T Y, Salvati M, Sanchez-Conde M, Sartori P, Satalecka K, Scalzotto V, Scapin V, Schweizer T, Shayduk M, Shinozaki K, Shore S N, Sidro N, Sierpowska-Bartosik A, Sillanpää A, Sitarek J, Sobczynska D, Spanier F, Stamerra A, Stark L S, Takalo L, Tavecchio F, Temnikov P, Tescaro D, Teshima M, Tluczykont M, Torres D F, Turini N, Vankov H, Venturini A, Vitale V, Wagner R M, Wittek W, Zabalza V, Zandanel F, Zanin R, Zapatero J, Acciari V, Aliu E, Arlen T, Beilicke M, Benbow W, Bradbury S M, Buckley J H, Bugaev V, Butt Y, Byrum K, Cannon A, Cesarini A, Chow Y C, Ciupik L, Cogan P, Colin P, Cui W, Daniel M K, Dickherber R, Duke C, Ergin T, Fegan S J, Finley J P, Finnegan G, Fortin P, Furniss A, Gall D, Gillanders G H, Guenette R, Gyuk G, Grube J, Hanna D, Holder J, Horan D, Hui C M, Humensky T Brian, Imran A, Kaaret P, Karlsson N, Kertzman M, Kieda D, Kildea J, Konopelko A, Krawczynski H, Krennrich F, Lang M J, LeBohec S, Maier G, McCann A, McCutcheon M, Milovanovic A, Moriarty P, Nagai T, Ong R A, Otte A N, Pandel D, Perkins J S, Pichel A, Pohl M, Ragan K, Reyes L C, Reynolds P T, Roache E, Rose H J, Schroedter M, Sembroski G H, Smith A W, Steele D, Swordy S P, Theiling M, Toner J A, Valcarcel L, Varlotta A, Wakely S P, Ward J E, Weekes T C, Weinstein A, Williams D A, Wissel S, Wood M, and Zitzer B
Subjects: campaign, Raigs còsmics, BL Lacertae: individual: Mrk421, galaxies: jets, X-Rays: Galaxies, gamma rays: observations, radiation mechanisms: nonthermal, bl-lacertae objects, blazars, Flux, Astrophysics, 01 natural sciences, 7. Clean energy, High Energy Gamma-ray Astronomy, law.invention, Raigs gamma, law, optical, MAGIC (telescope), Agile, blazr, X-ray, gamma, high energy observation, 010303 astronomy & astrophysics, webt, Physics, x-ray-spectra, Astrophysics (astro-ph), gamma-rays, lac objects, xmm-newton, Spectral energy distribution, Electrónica, Física nuclear, Raigs X, Electricidad, Flare, outburst, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, 0103 physical sciences, X-rays, BL Lacertae objects: individual (Mrk 421) – gamma rays: observations – galaxies: jets – radiation mechanisms: non-thermal – X-rays: galaxies, Blazar, Cosmic rays, 010308 nuclear & particles physics, Gamma rays, Astronomy and Astrophysics, Active Galactic Nuclei, radiation mechanisms: non-thermal, Light curve, Galaxies, Galàxies, MAGIC telescope, Space and Planetary Science, Very High Energy Gamma-ray Astronomy, ddc:520, AGILE satellite, bl lacertae objects: individual (mrk 421), Energy (signal processing), Lepton
Abstract: We present optical, X-ray, high energy ($\lessapprox 30$ GeV) and very high energy ($\gtrapprox 100$ GeV; VHE) observations of the high-frequency peaked blazar Mrk 421 taken between 2008 May 24 and June 23. A high energy $\gamma$-ray signal was detected by AGILE with \sqrt{TS}=4.5 on June 9--15, with $F(E>100 \mathrm{MeV})= 42^{+14}_{-12}\times 10^{-8}$ photons cm$^{-2}$ s$^{-1}$. This flaring state is brighter than the average flux observed by EGRET by a factor of $\sim$3, but still consistent with the highest EGRET flux. In hard X-rays (20-60 keV) SuperAGILE resolved a 5-day flare (June 9-15) peaking at $\sim$ 55 mCrab. SuperAGILE, RXTE/ASM and Swift/BAT data show a correlated flaring structure between soft and hard X-rays. Hints of the same flaring behavior are also detected in the simultaneous optical data provided by the GASP-WEBT. A Swift/XRT observation near the flaring maximum revealed the highest 2-10 keV flux ever observed from this source, of 2.6 $\times 10^{-9}$ erg cm$^{-2}$ s$^{-1}$ (i.e. > 100 mCrab). A peak synchrotron energy of $\sim$3 keV was derived, higher than typical values of $\sim$0.5-1 keV. VHE observations with MAGIC and VERITAS on June 6-8 show the flux peaking in a bright state, well correlated with the X-rays. This extraordinary set of simultaneous data, covering a twelve-decade spectral range, allowed for a deep analysis of the spectral energy distribution as well as of correlated light curves. The $\gamma$-ray flare can be interpreted within the framework of the synchrotron self-Compton model in terms of a rapid acceleration of leptons in the jet., Comment: accepted for publication in ApJL, 7 pages, 2 figures, 1 table
Published: 2009
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36. Observation of Markarian 421 in TeV gamma rays over a 14-year time span

Author: M. J. Lang, J. Tyler, J. H. Buckley, D. A. Carter-Lewis, E. Collins-Hughes, G. H. Gillanders, S. P. Wakely, Daniel Gall, L. Ciupik, N. Galante, E. Roache, A. N. Otte, H. Krawczynski, T. Reynolds, M. P. Connolly, D. S. Hanna, Ralph Bird, G. Finnegan, Geza Gyuk, K. Ragan, A. W. Smith, C. Duke, A. Pichel, G. H. Sembroski, Lucy Fortson, R. Welsing, Abraham D. Falcone, T. C. Arlen, V. Bugaev, Matthew R. Orr, J. P. Finley, Wei Cui, Y. Khassen, V. A. Acciari, T. Aune, T. C. Weekes, S. M. Bradbury, John Toner, A. C. Rovero, A. Cesarini, A. S. Madhavan, Wystan Benbow, Martin Pohl, John L. Quinn, P. Moriarty, R. A. Ong, K. G. Gibbs, J. Dumm, J. S. Perkins, S. J. Fegan, S. Federici, A. Weinstein, Stephanie Wissel, M. Schroedter, I. de la Calle Perez, A. Varlotta, A. Bouvier, P. Kaaret, J. E. Ward, David Kieda, M. Theiling, Sinéad M. Griffin, M. Kertzman, A. O'Faolain de Bhroithe, D. J. Fegan, T. J. N. Nelson, J. A. Gaidos, David A. Williams, I. Telezhinsky, T. B. Humensky, Julie McEnery, D. Horan, D. Petry, J. Grube, M. Vivier, and F. Krennrich
Subjects: multiwavelength observations, Cosmology and Nongalactic Astrophysics (astro-ph.CO), Active galactic nucleus, Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, Flux, Astrophysics, telescope, timing explorer, 01 natural sciences, Spectral line, law.invention, purl.org/becyt/ford/1 [https], Telescope, law, blazar markarian-421, emission, 0103 physical sciences, crab-nebula, flare, AGN, Blazar, tev gamma rays, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Markarian 421, 010308 nuclear & particles physics, markarian 421, Gamma ray, Astronomy, Institut für Physik und Astronomie, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], TeV gamma rays, Astronomía, Crab Nebula, correlated variability, active galactic nuclei, ddc:540, agn, Astrophysics - High Energy Astrophysical Phenomena, Markarian galaxies, CIENCIAS NATURALES Y EXACTAS, energy, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: The variability of the blazar Markarian 421 in TeV gamma rays over a 14-year time period has been explored with the Whipple 10 m telescope. It is shown that the dynamic range of its flux variations is large and similar to that in X-rays. A correlation between the X-ray and TeV energy bands is observed during some bright flares and when the complete data sets are binned on long timescales. The main database consists of 878.4 hours of observation with the Whipple telescope, spread over 783 nights. The peak energy response of the telescope was 400 GeV with 20% uncertainty. This is the largest database of any TeV-emitting active galactic nucleus (AGN) and hence was used to explore the variability profile of Markarian 421. The time-averaged flux from Markarian 421 over this period was 0.446$\pm$0.008 Crab flux units. The flux exceeded 10 Crab flux units on three separate occasions. For the 2000-2001 season the average flux reached 1.86 Crab units, while in the 1996-1997 season the average flux was only 0.23 Crab units., Comment: 29 pages, 15 figures. Accepted for publication in Astroparticle Physics
Published: 2014
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37. Discovery of TeV Gamma-ray Emission Toward Supernova Remnant SNR G78.2+2.1

Author: M. Kertzman, A. O'Faolain de Bhroithe, M. Schroedter, Vikram V. Dwarkadas, S. Vincent, Wei Cui, M. J. Lang, S. Thibadeau, A. N. Otte, M. P. Connolly, A. McCann, R. Mukherjee, D. B. Saxon, N. H. Park, J. Millis, T. Aune, J. E. Ward, A. Cesarini, P. Moriarty, John L. Quinn, T. B. Humensky, A. Furniss, Frank Krennrich, A. S. Madhavan, G. Tešić, Gernot Maier, H. Prokoph, A. Varlotta, Wystan Benbow, S. P. Wakely, Eric V. Gotthelf, E. Roache, J. P. Finley, S. Archambault, H. J. Rose, R. A. Ong, Ralph Bird, G. H. Sembroski, P. Kaaret, Amanda Weinstein, Abraham D. Falcone, R. Welsing, Vladimir Vassiliev, L. Ciupik, T. C. Weekes, J. Grube, D. Gall, Geza Gyuk, K. Tsurusaki, S. Federici, Manel Errando, T. C. Arlen, J. H. Buckley, G. H. Gillanders, P. Majumdar, T. J. N. Nelson, S. McArthur, N. Galante, S. Godambe, Dirk Pandel, S. Griffin, G. Finnegan, C. Skole, C. Duke, David A. Williams, N. Karlsson, G. D. Şentürk, T. Weisgarber, H. Huan, E. Aliu, I. Telezhinsky, K. Lee, Jamie Holder, A. Popkow, J. Tyler, A. Bouvier, D. S. Hanna, V. Bugaev, J. S. Perkins, Martin Pohl, Q. Feng, J. Dumm, P. T. Reynolds, David Kieda, M. Theiling, Lucy Fortson, Karen Byrum, S. M. Bradbury, A. Cannon, E. Collins-Hughes, H. Krawczynski, M. Beilicke, M. Orr, G. Hughes, K. Ragan, B. Zitzer, J. Ruppel, R. Dickherber, Y. Khassen, and Luis C. Reyes
Subjects: catalog, Astrophysics::High Energy Astrophysical Phenomena, Hadron, Flux, FOS: Physical sciences, Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, cosmic rays, Observatory, 0103 physical sciences, origin, Supernova remnant, 010303 astronomy & astrophysics, 2cg078+2, Astrophysics::Galaxy Astrophysics, acceleration of particles, Physics, search, High Energy Astrophysical Phenomena (astro-ph.HE), particle-acceleration, 010308 nuclear & particles physics, hess, Gamma ray, Institut für Physik und Astronomie, counterpart, Astronomy and Astrophysics, gamma rays: general, Particle acceleration, Crab Nebula, Space and Planetary Science, ism: supernova remnants, ddc:520, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, fermi
Abstract: We report the discovery of an unidentified, extended source of very-high-energy (VHE) gamma-ray emission, VER J2019+407, within the radio shell of the supernova remnant SNR G78.2+2.1, using 21.4 hours of data taken by the VERITAS gamma-ray observatory in 2009. These data confirm the preliminary indications of gamma-ray emission previously seen in a two-year (2007-2009) blind survey of the Cygnus region by VERITAS. VER J2019+407, which is detected at a post-trials significance of 7.5 standard deviations in the 2009 data, is localized to the northwestern rim of the remnant in a region of enhanced radio and X-ray emission. It has an intrinsic extent of 0.23^{\circ} \pm 0.03^{\circ} (stat)+0.04^{\circ}_{-0.02}^{\circ}(sys) and its spectrum is well-characterized by a differential power law (dN/dE = N_0 \times (E/TeV)^{-\Gamma}) with a photon index of {\Gamma} = 2.37 \pm 0.14 (stat) \pm 0.20 (sys) and a flux normalization of N0 = 1.5 \pm 0.2 (stat) \pm 0.4(sys) \times 10^-12 ph TeV^{-1} cm^{-2} s^{-1}. This yields an integral flux of 5.2 \pm 0.8 (stat) \pm 1.4 (sys) \times 10^-12 ph cm^{-2} s^{-1} above 320 GeV, corresponding to 3.7% of the Crab Nebula flux. We consider the relationship of the TeV gamma-ray emission with the GeV gamma-ray emission seen from SNR G78.2+2.1 as well as that seen from a nearby cocoon of freshly accelerated cosmic rays. Multiple scenarios are considered as possible origins for the TeV gamma-ray emission, including hadronic particle acceleration at the supernova remnant shock., Comment: 18 pages, 5 figures, accepted for publication in ApJ
Published: 2013
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38. Discovery of TeV Gamma-ray Emission from CTA 1 by VERITAS

Author: A. N. Otte, G. H. Sembroski, M. P. Connolly, E. Aliu, T. J. N. Nelson, R. Welsing, K. Lee, L. Ciupik, M. Theiling, P. Moriarty, Eric V. Gotthelf, Geza Gyuk, N. Karlsson, J. P. Finley, Wei Cui, Q. Feng, Gernot Maier, T. C. Weekes, I. Telezhinsky, Jamie Holder, S. Thibadeau, D. Gall, Oleg Kargaltsev, A. O'Faolain de Bhroithe, H. Krawczynski, A. Furniss, N. Galante, S. P. Wakely, R. Mukherjee, R. A. Ong, E. Roache, R. Dickherber, H. Prokoph, S. Vincent, A. S. Madhavan, Wystan Benbow, Abraham D. Falcone, S. Griffin, G. Finnegan, A. W. Smith, Mallory S. E. Roberts, S. McArthur, C. Duke, B. Zitzer, P. T. Reynolds, P. Kaaret, K. Ragan, J. Tyler, F. Krennrich, Y. Khassen, M. Schroedter, A. Bouvier, Vikram V. Dwarkadas, M. Vivier, J. Grube, M. Beilicke, Manel Errando, D. Staszak, S. Federici, J. H. Buckley, P. Majumdar, J. S. Perkins, David Kieda, D. B. Saxon, E. Collins-Hughes, Luis C. Reyes, N. H. Park, David A. Williams, Patrick Slane, M. Orr, T. B. Humensky, T. Aune, S. Godambe, G. Hughes, T. Arlen, Lucy Fortson, A. Cesarini, John L. Quinn, Martin Pohl, J. Dumm, Vladimir Vassiliev, A. Varlotta, M. J. Lang, A. Weinstein, K. Tsurusaki, G. H. Gillanders, D. S. Hanna, G. Tešić, V. Bugaev, S. Archambault, and A. McCann
Subjects: catalog, gamma-rays: stars, Photon, Astrophysics::High Energy Astrophysical Phenomena, supernova remnant cta-1, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, 01 natural sciences, Pulsar wind nebula, atmospheric cherenkov telescopes, Pulsar, Observatory, hess j1825-137, evolution, 0103 physical sciences, pulsations, crab-nebula, Supernova remnant, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Spectral index, pulsars: individual (psr j0007+7303), 010308 nuclear & particles physics, Gamma ray, Astronomy and Astrophysics, x-rays: individual (rx j0007.0+7303), astronomy, supernovae: individual (g119.5+10.2), x-ray, Space and Planetary Science, ddc:520, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, pulsar-wind nebulae, Fermi Gamma-ray Space Telescope
Abstract: We report the discovery of TeV gamma-ray emission coincident with the shell-type radio supernova remnant (SNR) CTA 1 using the VERITAS gamma-ray observatory. The source, VER J0006+729, was detected as a 6.5 standard deviation excess over background and shows an extended morphology, approximated by a two-dimensional Gaussian of semi-major (semi-minor) axis 0.30 degree (0.24 degree) and a centroid 5' from the Fermi gamma-ray pulsar PSR J0007+7303 and its X-ray pulsar wind nebula (PWN). The photon spectrum is well described by a power-law dN/dE = N_0 (E/3 TeV)^(-\Gamma), with a differential spectral index of \Gamma = 2.2 +- 0.2_stat +- 0.3_sys, and normalization N_0 = (9.1 +- 1.3_stat +- 1.7_sys) x 10^(-14) cm^(-2) s^(-1) TeV^(-1). The integral flux, F_\gamma = 4.0 x 10^(-12) erg cm^(-2) s^(-1) above 1 TeV, corresponds to 0.2% of the pulsar spin-down power at 1.4 kpc. The energetics, co-location with the SNR, and the relatively small extent of the TeV emission strongly argue for the PWN origin of the TeV photons. We consider the origin of the TeV emission in CTA 1., Comment: 10 pages, 9 figures, accepted for publication in ApJ
Published: 2012
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39. Search for a correlation between very-high-energy gamma rays and giant radio pulses in the Crab pulsar

Author: Matthias Beilicke, J. P. Dumm, Martin Pohl, G. Tešić, Q. Feng, V. Bugaev, T. Aune, A. Varlotta, R. Dickherber, T. B. Humensky, T. J. N. Nelson, S. Thibadeau, A. McCann, M. P. Connolly, Maxim Lyutikov, R. G. Wagner, Henric Krawczynski, E. Aliu, A. J.R. Weinstein, I. Telezhinsky, Jamie Holder, F. Krennrich, H. Prokoph, S. Vincent, L. C. Reyes, K. Lee, Sinéad M. Griffin, D. B. Saxon, Karen Byrum, D. S. Hanna, N. H. Park, Lucy Fortson, D. Staszak, K. Tsurusaki, M. Theiling, T. C. Arlen, K. Ragan, Gareth Hughes, Amy Furniss, P. Kaaret, M. Schroedter, B. Zitzer, E. Collins-Hughes, Gernot Maier, M. J. Lang, G. H. Gillanders, S. Godambe, S. P. Wakely, G. H. Sembroski, Daniel Gall, R. Welsing, A. N. Otte, Matthew R. Orr, L. Ciupik, A. Cesarini, R. A. Ong, V. Kondratiev, David A. Williams, John L. Quinn, A. Bouvier, J. H. Buckley, A. D. Falcone, J. P. Finley, M. Vivier, T. C. Weekes, S. LeBohec, David Kieda, S. McArthur, Y. Khassen, P. T. Reynolds, Geza Gyuk, Pratik Majumdar, S. Archambault, Reshmi Mukherjee, Wystan Benbow, J. S. Perkins, P. Moriarty, Nicola Galante, J. Grube, N. Karlsson, G. Finnegan, A. W. Smith, A. S Madhavan, C. Duke, E. Roache, G. D. Şentürk, H. Huan, A. O'Faolain de Bhroithe, S. Federici, and Wei Cui
Subjects: High energy, nebula, pulsars: individual: b0531+21, Flux, FOS: Physical sciences, Astrophysics, 01 natural sciences, Arrival time, law.invention, Radio telescope, Telescope, law, Time windows, 0103 physical sciences, emission, photons, rays: stars, geminga, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), model, 010308 nuclear & particles physics, Crab Pulsar, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, telescopes, universe, Space and Planetary Science, range, Astrophysics - High Energy Astrophysical Phenomena
Abstract: We present the results of a joint observational campaign between the Green Bank radio telescope and the VERITAS gamma-ray telescope, which searched for a correlation between the emission of very-high-energy (VHE) gamma rays ($E_{\gamma} >$ 150 GeV) and Giant Radio Pulses (GRPs) from the Crab pulsar at 8.9 GHz. A total of 15366 GRPs were recorded during 11.6 hours of simultaneous observations, which were made across four nights in December 2008 and in November and December 2009. We searched for an enhancement of the pulsed gamma-ray emission within time windows placed around the arrival time of the GRP events. In total, 8 different time windows with durations ranging from 0.033 ms to 72 s were positioned at three different locations relative to the GRP to search for enhanced gamma-ray emission which lagged, led, or was concurrent with, the GRP event. Further, we performed separate searches on main pulse GRPs and interpulse GRPs and on the most energetic GRPs in our data sample. No significant enhancement of pulsed VHE emission was found in any of the preformed searches. We set upper limits of 5-10 times the average VHE flux of the Crab pulsar on the flux simultaneous with interpulse GRPs on single-rotation-period time scales. On $\sim$8-second time scales around interpulse GRPs, we set an upper limit of 2-3 times the average VHE flux. Within the framework of recent models for pulsed VHE emission from the Crab pulsar, the expected VHE-GRP emission correlations are below the derived limits., Comment: 12 pages, 12 figures, To appear in The Astrophysical Journal
Published: 2012
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40. VERITAS Observations of the Nova in V407 Cygni

Author: H. J. Rose, A. Cesarini, John L. Quinn, Gernot Maier, S. Griffin, M. Orr, A. Varlotta, Martin Pohl, D. Staszak, G. Hughes, E. Aliu, S. P. Wakely, J. Dumm, S. Vincent, K. Lee, D. S. Hanna, G. Tešić, M. Theiling, T. Weisgarber, S. M. Bradbury, A. Cannon, P. Kaaret, J. P. Finley, S. Godambe, M. Kertzman, T. B. Humensky, T. C. Weekes, K. Tsurusaki, Geza Gyuk, Dirk Pandel, M. J. Lang, S. Thibadeau, H. Krawczynski, V. Bugaev, T. Arlen, N. Galante, J. Ruppel, M. Schroedter, Vikram V. Dwarkadas, B. Zitzer, G. Finnegan, J. Grube, A. W. Smith, Manel Errando, S. Archambault, Lucy Fortson, G. H. Sembroski, M. Vivier, Abraham D. Falcone, C. Duke, M. Beilicke, Wystan Benbow, J. H. Buckley, David A. Williams, R. Welsing, D. B. Saxon, H. Huan, N. H. Park, K. Ragan, S. McArthur, I. Telezhinsky, David Kieda, Paul D. Nuñez, A. McCann, Wei Cui, Jamie Holder, P. Majumdar, E. Roache, P. Moriarty, J. E. Ward, G. Decerprit, C. Skole, A. Weinstein, H. Prokoph, J. Tyler, Karen Byrum, R. A. Ong, A. N. Otte, M. P. Connolly, Q. Feng, T. Aune, F. Krennrich, J. S. Perkins, E. Collins-Hughes, L. Ciupik, J. Millis, A. Bouvier, P. T. Reynolds, D. Gall, R. Mukherjee, Luis C. Reyes, N. Karlsson, A. Furniss, R. Dickherber, and Y. Khassen
Subjects: High energy, blast wave, FOS: Physical sciences, Radiation imaging, Flux, array, Astrophysics, galactic plane, 01 natural sciences, law.invention, Telescope, law, 0103 physical sciences, novae, cataclysmic variables, 010306 general physics, 010303 astronomy & astrophysics, Zenith, white dwarfs, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, gamma rays: general, Nova (laser), gamma-ray emission, Astrophysics - Astrophysics of Galaxies, rs-ophiuchi, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), cherenkov telescopes, Astrophysics - High Energy Astrophysical Phenomena, 2006 outburst, discovery
Abstract: We report on very high energy (E > 100 GeV) gamma-ray observations of V407 Cygni, a symbiotic binary that underwent a nova outburst producing 0.1-10 GeV gamma rays during 2010 March 10-26. Observations were made with the Very Energetic Radiation Imaging Telescope Array System during 2010 March 19-26 at relatively large zenith angles, due to the position of V407 Cyg. An improved reconstruction technique for large zenith angle observations is presented and used to analyze the data. We do not detect V407 Cygni and place a differential upper limit on the flux at 1.6 TeV of 2.3 \times 10^(-12) erg cm^(-2) s^(-1) (at the 95% confidence level). When considered jointly with data from Fermi-LAT, this result places limits on the acceleration of very high energy particles in the nova., 17 pages, 4 figures, accepted for publication in ApJ
Published: 2012
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41. Discovery of High-energy and Very High Energy Gamma-ray Emission from the Blazar RBS 0413

Author: D. Gall, M. P. Connolly, R. Mukherjee, G. H. Sembroski, S. McArthur, T. B. Humensky, S. Archambault, S. Griffin, P. Fortin, H. J. Rose, A. Pichel, P. T. Reynolds, J. E. Ward, A. Cesarini, A. N. Otte, John L. Quinn, A. S. Madhavan, Wystan Benbow, A. Varlotta, P. Majumdar, I. Telezhinsky, J. Grube, R. A. Ong, Manel Errando, Jamie Holder, A. Bouvier, M. J. Lang, M. Theiling, J. P. Finley, S. M. Bradbury, K. Ragan, Wei Cui, S. Thibadeau, T. Aune, Markus Böttcher, T. C. Weekes, Abraham D. Falcone, G. Decerprit, L. C. Reyes, A. McCann, H. Prokoph, E. Roache, N. Palma, Geza Gyuk, G. Tešić, E. Aliu, D. Horan, J. Ruppel, L. Ciupik, Gareth Hughes, M. Kertzman, B. Zitzer, T. Weisgarber, K. Lee, D. S. Hanna, V. Bugaev, A. Weinstein, M. Vivier, David A. Williams, H. Krawczynski, K. Tsurusaki, S. Godambe, T. Arlen, Lucy Fortson, Martin Pohl, J. Dumm, Keith Hawkins, Karen Byrum, M. Schroedter, M. Beilicke, David Kieda, J. H. Buckley, J. S. Perkins, E. Collins-Hughes, F. Krennrich, M. Orr, Q. Feng, A. Cannon, P. Kaaret, D. B. Saxon, N. H. Park, Gernot Maier, S. P. Wakely, N. Galante, G. Finnegan, A. W. Smith, G. D. Şentürk, H. Huan, Paolo De Coppi, P. Moriarty, A. Furniss, D. Staszak, R. Dickherber, Y. Khassen, and N. Karlsson
Subjects: catalog, Astrophysics::High Energy Astrophysical Phenomena, bl-lacertae objects, Flux, FOS: Physical sciences, Astrophysics, swift ultraviolet/optical telescope, bright blazars, 7. Clean energy, 01 natural sciences, law.invention, Telescope, law, gamma rays: galaxies, 0103 physical sciences, bl lacertae objects: individual (rbs 0413-ver j0319+187), Blazar, Nuclear Experiment, 010303 astronomy & astrophysics, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), model, 010308 nuclear & particles physics, Institut für Physik und Astronomie, Astronomy and Astrophysics, lac objects, Synchrotron, radiation, large-area telescope, Crab Nebula, mission, 13. Climate action, Space and Planetary Science, active galactic nuclei, Spectral energy distribution, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, BL Lac object, Fermi Gamma-ray Space Telescope
Abstract: We report on the discovery of high-energy (HE; E > 0.1 GeV) and very high-energy (VHE; E > 100 GeV) gamma-ray emission from the high-frequency-peaked BL Lac object RBS 0413. VERITAS, a ground-based gamma-ray observatory, detected VHE gamma rays from RBS 0413 with a statistical significance of 5.5 standard deviations (sigma) and a gamma-ray flux of (1.5 \pm 0.6stat \pm 0.7syst) \times 10^(-8) photons m^(-2) s^(-1) (\sim 1% of the Crab Nebula flux) above 250 GeV. The observed spectrum can be described by a power law with a photon index of 3.18 \pm 0.68stat \pm 0.30syst. Contemporaneous observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope detected HE gamma rays from RBS 0413 with a statistical significance of more than 9 sigma, a power-law photon index of 1.57 \pm 0.12stat +0.11sys -0.12sys and a gamma-ray flux between 300 MeV and 300 GeV of (1.64 \pm 0.43stat +0.31sys -0.22sys) \times 10^(-5) photons m^(-2) s^(-1). We present the results from Fermi-LAT and VERITAS, including a spectral energy distribution modeling of the gamma-ray, quasi-simultaneous X-ray (Swift-XRT), ultraviolet (Swift-UVOT) and R-band optical (MDM) data. We find that, if conditions close to equipartition are required, both the combined synchrotron self-Compton/external-Compton and the lepto-hadronic models are preferred over a pure synchrotron self-Compton model., 14 pages, 3 figures, accepted to ApJ, corresponding author: G. D. Senturk
Published: 2012
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42. VERITAS deep observations of the dwarf spheroidal galaxy Segue 1

Author: A. McCann, I. Telezhinsky, R. A. Ong, Jamie Holder, T. Arlen, G. Teić, Philip Kaaret, A. S. Madhavan, Wystan Benbow, S. Vincent, N. Galante, G. D. Entürk, A. Bouvier, G. H. Sembroski, S. McArthur, G. Finnegan, A. W. Smith, S. M. Bradbury, Gernot Maier, M. P. Connolly, S. P. Wakely, Abraham D. Falcone, A. Varlotta, T. Aune, J. Grube, A. Cannon, E. Roache, H. Huan, Matthew R. Orr, R. Dickherber, Manel Errando, Daniel Gall, Karen Byrum, K. Ragan, S. Thibadeau, J. H. Buckley, E. Collins-Hughes, M. Kertzman, Lucy Fortson, J. S. Perkins, H. J. Rose, G. Decerprit, V. Bugaev, Q. Feng, P. Moriarty, M. Vivier, M. Beilicke, M. Schroedter, David A. Williams, Y. Khassen, T. Weisgarber, D. Staszak, J. E. Ward, S. Archambault, Reshmi Mukherjee, T. B. Humensky, A. Furniss, Francesc Ferrer, Geza Gyuk, D. B. Saxon, A. Cesarini, John L. Quinn, B. Zitzer, P. T. Reynolds, N. H. Park, Henric Krawczynski, L. Ciupik, P. Majumdar, E. Aliu, K. Tsurusaki, Jodi Christiansen, C. Skole, D. Hanna, Martin Pohl, S. Godambe, J. Dumm, K. Lee, L. C. Reyes, Vladimir Vassiliev, N. Karlsson, J. P. Finley, T. C. Weekes, Wei Cui, H. Prokoph, R. G. Wagner, David Kieda, M. Theiling, J. Ruppel, Amanda Weinstein, A. N. Otte, Frank Krennrich, Sinéad M. Griffin, and Gareth Hughes
Subjects: Nuclear and High Energy Physics, Astrophysics::High Energy Astrophysical Phenomena, Dwarf galaxy problem, cosmic-rays, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, dark-matter annihilation, 01 natural sciences, local group, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), 0103 physical sciences, upper limits, ddc:530, 010303 astronomy & astrophysics, Light dark matter, galactic-center, Astrophysics::Galaxy Astrophysics, Dwarf galaxy, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Hot dark matter, Institut für Physik und Astronomie, Astronomy, Segue, gamma-ray emission, Galaxy, Dwarf spheroidal galaxy, Dark matter halo, large-area telescope, cherenkov telescopes, Astrophysics - High Energy Astrophysical Phenomena, magic telescope, empirical-models
Abstract: The VERITAS array of Cherenkov telescopes has carried out a deep observational program on the nearby dwarf spheroidal galaxy Segue 1. We report on the results of nearly 48 hours of good quality selected data, taken between January 2010 and May 2011. No significant $\gamma$-ray emission is detected at the nominal position of Segue 1, and upper limits on the integrated flux are derived. According to recent studies, Segue 1 is the most dark matter-dominated dwarf spheroidal galaxy currently known. We derive stringent bounds on various annihilating and decaying dark matter particle models. The upper limits on the velocity-weighted annihilation cross-section are $\mathrm{^{95% CL} \lesssim 10^{-23} cm^{3} s^{-1}}$, improving our limits from previous observations of dwarf spheroidal galaxies by at least a factor of two for dark matter particle masses $\mathrm{m_{\chi}\gtrsim 300 GeV}$. The lower limits on the decay lifetime are at the level of $\mathrm{\tau^{95% CL} \gtrsim 10^{24} s}$. Finally, we address the interpretation of the cosmic ray lepton anomalies measured by ATIC and PAMELA in terms of dark matter annihilation, and show that the VERITAS observations of Segue 1 disfavor such a scenario., Comment: Added recently published erratum at the end of the original article
Published: 2012
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43. Veritas observations of day-scale flaring of M 87 in 2010 April

Author: R. Dickherber, A. Cesarini, John L. Quinn, S. Thibadeau, Sinéad M. Griffin, M. Kertzman, J. P. Finley, K. Tsurusaki, H. Prokoph, P. Kaaret, Geza Gyuk, J. Ruppel, R. Guenette, T. C. Weekes, Pratik Majumdar, A. Pichel, S. Godambe, Nahee Park, Reshmi Mukherjee, M. P. Connolly, A. McCann, H. J. Rose, K. L. Byrum, E. Collins-Hughes, J. Tyler, N. Karlsson, J. H. Buckley, E. Aliu, A. N. Otte, David A. Williams, Gernot Maier, L. Ciupik, G. Tešić, C. M. Hui, Wystan Benbow, Jamie Holder, Henric Krawczynski, Daniel Gall, A. Varlotta, M. J. Lang, A. J.R. Weinstein, L. C. Reyes, C. Skole, Amy Furniss, Matthias Beilicke, M. Pohl, Wei Cui, D. Staszak, Paul D. Nuñez, S. M. Bradbury, K. Ragan, R. A. Ong, Thomas Weisgarber, Matthew R. Orr, S. P. Wakely, V. V. Vassiliev, G. Hughes, F. Krennrich, A. D. Falcone, A. Bouvier, J. S. Perkins, S. LeBohec, J. E. Ward, A. Cannon, M. Theiling, Lucy Fortson, D. B. Saxon, T. Aune, S. McArthur, V. Bugaev, G. H. Sembroski, T. B. Humensky, B. Zitzer, Manel Errando, D. B. Kieda, G. Finnegan, A. S Madhavan, C. Duke, E. Roache, G. D. Şentürk, H. Huan, P. Moriarty, Nicola Galante, J. Grube, D. S. Hanna, T. C. Arlen, A. Imran, P. T. Reynolds, M. Schroedter, S. Vincent, and M. Vivier
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Radio galaxy, Ciencias Físicas, Phase (waves), FOS: Physical sciences, Flux, radio galaxy m87, Astrophysics, Electron, telescope, agns, 01 natural sciences, 7. Clean energy, Spectral line, blazar, law.invention, purl.org/becyt/ford/1 [https], law, jet, gamma rays: galaxies, 0103 physical sciences, galaxies: individual (m 87, ver j1230+123), hst-1, 010303 astronomy & astrophysics, Physics, Spectral index, tev emission, variability, 010308 nuclear & particles physics, Institut für Physik und Astronomie, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], gamma-ray emission, Astronomía, Space and Planetary Science, individual (M 87, VER J1230+123) [galaxies], Rise time, galaxies [gamma rays], CIENCIAS NATURALES Y EXACTAS, supermassive black-hole, Astrophysics - Cosmology and Nongalactic Astrophysics, Flare
Abstract: VERITAS has been monitoring the very-high-energy (VHE; >100GeV) gamma-ray activity of the radio galaxy M87 since 2007. During 2008, flaring activity on a timescale of a few days was observed with a peak flux of (0.70 +- 0.16) X 10^{-11} cm^{-2} s^{-1} at energies above 350GeV. In 2010 April, VERITAS detected a flare from M87 with peak flux of (2.71 +- 0.68) X 10^{-11} cm^{-2} s^{-1} for E>350GeV. The source was observed for six consecutive nights during the flare, resulting in a total of 21 hr of good quality data. The most rapid flux variation occurred on the trailing edge of the flare with an exponential flux decay time of 0.90^{+0.22}_{-0.15} days. The shortest detected exponential rise time is three times as long, at 2.87^{+1.65}_{-0.99} days. The quality of the data sample is such that spectral analysis can be performed for three periods: rising flux, peak flux, and falling flux. The spectra obtained are consistent with power-law forms. The spectral index at the peak of the flare is equal to 2.19 +- 0.07. There is some indication that the spectrum is softer in the falling phase of the flare than the peak phase, with a confidence level corresponding to 3.6 standard deviations. We discuss the implications of these results for the acceleration and cooling rates of VHE electrons in M87 and the constraints they provide on the physical size of the emitting region., Accepted for publication in ApJ; 17 pages, 5 figures; Corresponding author: C. M. Hui
Published: 2012
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44. Multiwavelength observations of the AGN 1ES 0414+009 with veritas, FERMI-LAT, SWIFT-XRT, AND MDM

Author: E. Aliu, S. Archambault, T. Arlen, T. Aune, M. Beilicke, W. Benbow, M. Böttcher, A. Bouvier, V. Bugaev, A. Cannon, A. Cesarini, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, J. Dumm, M. Errando, A. Falcone, S. Federici, Q. Feng, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, S. Godambe, S. Griffin, J. Grube, G. Gyuk, D. Hanna, J. Holder, H. Huan, G. Hughes, C. M. Hui, A. Imran, O. Jameil, P. Kaaret, N. Karlsson, M. Kertzman, J. Kerr, Y. Khassen, D. Kieda, H. Krawczynski, F. Krennrich, M. J. Lang, K. Lee, A. S. Madhavan, P. Majumdar, S. McArthur, A. McCann, P. Moriarty, R. Mukherjee, T. Nelson, A. O'Faoláin de Bhróithe, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, A. Pichel, M. Pohl, J. Quinn, K. Ragan, P. T. Reynolds, E. Roache, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, G. D. Şentürk, A. W. Smith, D. Staszak, M. Stroh, I. Telezhinsky, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, A. Varlotta, V. V. Vassiliev, M. Vivier, S. P. Wakely, J. E. Ward, A. Weinstein, R. Welsing, D. A. Williams, and B. Zitzer
Subjects: stars, Photon, Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, blazars, Flux, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, telescope, 01 natural sciences, Power law, purl.org/becyt/ford/1 [https], gamma-ray astronomy, 0103 physical sciences, gamma rays: galaxies, emission, bl lacertae objects: individual (1es 0414+009, erj0416+011), Nuclear Experiment, 010303 astronomy & astrophysics, Cherenkov radiation, Physics, search, High Energy Astrophysical Phenomena (astro-ph.HE), 010308 nuclear & particles physics, Institut für Physik und Astronomie, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], sample, Astronomía, Crab Nebula, individual (1ES 0414+009, VERJ0416+011) [BL Lacertae objects], Space and Planetary Science, bl lacertae object, galaxies [gamma rays], Spectral energy distribution, High Energy Physics::Experiment, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, discovery, Fermi Gamma-ray Space Telescope, BL Lac object
Abstract: We present observations of the BL Lac object 1ES 0414+009 in the >200 GeV gamma-ray band by the VERITAS array of Cherenkov telescopes. 1ES 0414+009 was observed by VERITAS between January 2008 and February 2011, resulting in 56.2 hours of good quality pointed observations. These observations resulted in a detection of 822 events from the source corresponding to a statistical significance of 6.4 standard deviations (6.4 sigma) above the background. The source flux, showing no evidence for variability, is measured as 5.2 +/- 1.1_stat +/- 2.6_sys * 10^-12 photons cm^-2 s^-1 above 200 GeV, equivalent to approximately 2% of the Crab Nebula flux above this energy. The differential photon spectrum from 230 GeV to 850 GeV is well fit by a power law with an photon index of Gamma 3.4 +/- 0.5_stat +/- 0.3_sys and a flux normalization of 1.6 +/- 0.3_stat +/- 0.8_sys * 10^-11 photons cm^-2 s^-1 at 300 GeV. We also present multiwavelength results taken in the optical (MDM), X-ray (Swift-XRT), and GeV (Fermi-LAT) bands and use these results to construct a broadband spectral energy distribution (SED). Modeling of this SED indicates that homogenous one-zone leptonic scenarios are not adequate to describe emission from the system, with a lepto-hadronic model providing a better fit to the data., Accepted for publication in The Astrophysical Journal
Published: 2012
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45. Constraints on Cosmic Rays, Magnetic Fields, and Dark Matter from Gamma-Ray Observations of the Coma Cluster of Galaxies with VERITAS and Fermi

Author: T. Arlen, T. Aune, M. Beilicke, W. Benbow, A. Bouvier, J. H. Buckley, V. Bugaev, K. Byrum, A. Cannon, A. Cesarini, L. Ciupik, E. Collins-Hughes, M. P. Connolly, W. Cui, R. Dickherber, J. Dumm, A. Falcone, S. Federici, Q. Feng, J. P. Finley, G. Finnegan, L. Fortson, A. Furniss, N. Galante, D. Gall, S. Godambe, S. Griffin, J. Grube, G. Gyuk, J. Holder, H. Huan, G. Hughes, T. B. Humensky, A. Imran, P. Kaaret, N. Karlsson, M. Kertzman, Y. Khassen, D. Kieda, H. Krawczynski, F. Krennrich, K. Lee, A. S Madhavan, G. Maier, P. Majumdar, S. McArthur, A. McCann, P. Moriarty, R. Mukherjee, T. Nelson, A. O’Faoláin de Bhróit, R. A. Ong, M. Orr, A. N. Otte, N. Park, J. S. Perkins, M. Pohl, H. Prokoph, J. Quinn, K. Ragan, L. C. Reyes, P. T. Reynolds, E. Roache, J. Ruppel, D. B. Saxon, M. Schroedter, G. H. Sembroski, C. Skole, A. W. Smith, I. Telezhinsky, G. Tešić, M. Theiling, S. Thibadeau, K. Tsurusaki, A. Varlotta, M. Vivier, S. P. Wakely, J. E. Ward, A. Weinstein, R. Welsing, D. A. Williams, B. Zitzer, C. Pfrommer, and A. Pinzke
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO), Astrophysics::High Energy Astrophysical Phenomena, Dark matter, nonthermal emission, FOS: Physical sciences, Coma (optics), Cosmic ray, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, galaxies: clusters: individual (coma (aco 1656)), magnetic fields, dark matter, large-scale structure, shock-waves, atmospheric cherenkov telescopes, diffuse radio-emission, cosmic rays, all-sky survey, Coma Cluster, upper limits, galactic-center, Galaxy cluster, Cherenkov radiation, gamma rays: galaxies: clusters, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Institut für Physik und Astronomie, Astronomy and Astrophysics, source catalog, Galaxy, x-ray, galaxies: clusters: general, Space and Planetary Science, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, Fermi Gamma-ray Space Telescope
Abstract: Observations of radio halos and relics in galaxy clusters indicate efficient electron acceleration. Protons should likewise be accelerated, suggesting that clusters may also be sources of very high-energy (VHE; E>100 GeV) gamma-ray emission. We report here on VHE gamma-ray observations of the Coma galaxy cluster with the VERITAS array of imaging Cherenkov telescopes, with complementing Fermi-LAT observations at GeV energies. No significant gamma-ray emission from the Coma cluster was detected. Integral flux upper limits at the 99% confidence level were measured to be on the order of (2-5)*10^-8\ ph. m^-2 s^-1 (VERITAS, >220 GeV} and ~2*10^-6 ph. m^-2 s^-1 (Fermi, 1-3 GeV), respectively. We use the gamma-ray upper limits to constrain CRs and magnetic fields in Coma. Using an analytical approach, the CR-to-thermal pressure ratio is constrained to be < 16% from VERITAS data and < 1.7% from Fermi data (averaged within the virial radius). These upper limits are starting to constrain the CR physics in self-consistent cosmological cluster simulations and cap the maximum CR acceleration efficiency at structure formation shocks to be, ApJ in press
Published: 2012
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46. TeV and Multi-wavelength Observations of Mrk 421 in 2006-2008

Author: Carolin Villforth, Matthias Beilicke, P. Kaaret, A. Pichel, M. Ouellette, S. Vincent, A. Pease, R. G. Wagner, Gernot Maier, J. E. Ward, C. M. Hui, Wystan Benbow, A. Sillanpää, Michael T. Carini, S. P. Wakely, Daniel Gall, M. McCutcheon, K. Ragan, A. Konopelko, Andrei Berdyugin, S. P. Swordy, D. S. Hanna, T. C. Arlen, A. Imran, S. McArthur, V. A. Acciari, R. Dickherber, M. Kertzman, N. Karlsson, D. Steele, Karen Byrum, T. B. Humensky, P. T. Reynolds, S. Thibadeau, E. Nieppola, E. Lindfors, G. H. Sembroski, M. Schroedter, J. S. Perkins, K. Nilsson, D. Boltuch, Hugh D. Aller, G. Demet Senturk, A. C. Rovero, R. Guenette, Geza Gyuk, P. Moriarty, Nicola Galante, Stephanie Wissel, Wei Cui, Amy Furniss, M. J. Lang, M. F. Aller, Alfred Garson, A. Cesarini, David A. Williams, T. Aune, L. O. Takalo, Jamie Holder, R. A. Ong, Thomas Weisgarber, G. H. Gillanders, S. Godambe, David Kieda, L. C. Reyes, John L. Quinn, H. J. Rose, G. Finnegan, C. Duke, Robert J. Walters, E. Roache, Matthew J.A. Wood, S. M. Bradbury, V. V. Vassiliev, Abraham D. Falcone, A. C. Sadun, Lucy Fortson, E. Aliu, Henric Krawczynski, A. J.R. Weinstein, A. Varlotta, L. Ciupik, J. Sainio, A. Cannon, D. Pandel, V. Bugaev, T. Montaruli, Talvikki Hovatta, M. Baker, Anne Lähteenmäki, Kyle Cook, B. Zitzer, J. Grube, S. Smith, J. P. Finley, T. C. Weekes, J. H. Buckley, F. Krennrich, M. Pasanen, M. Theiling, A. N. Otte, Merja Tornikoski, Jeremy D. Maune, D. Barnaby, M. Pohl, and K. Lee
Subjects: individual (Mrk 421) [BL Lacertae objects], galaxies [Gamma rays], Ciencias Físicas, Astrophysics::High Energy Astrophysical Phenomena, bl-lacertae objects, FOS: Physical sciences, Multi wavelength, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, ray timing explorer, energy gamma-rays, 01 natural sciences, Spectral line, law.invention, Telescope, purl.org/becyt/ford/1 [https], Observatory, law, blazar markarian-421, 0103 physical sciences, gamma rays: galaxies, Blazar, 010303 astronomy & astrophysics, x-rays: galaxies, Cherenkov radiation, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, particle-acceleration, 010308 nuclear & particles physics, Spectral density, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], galaxies: jets, Redshift, Astronomía, large-area telescope, x-ray, 13. Climate action, Space and Planetary Science, correlated variability, nuclei [Galaxies], active galactic nuclei, jets [Galaxies], bl lacertae objects: individual (mrk 421), galaxies: nuclei, Astrophysics - High Energy Astrophysical Phenomena, CIENCIAS NATURALES Y EXACTAS, log-parabolic spectra
Abstract: We report on TeV gamma-ray observations of the blazar Mrk 421 (redshift of 0.031) with the VERITAS observatory and the Whipple 10m Cherenkov telescope. The excellent sensitivity of VERITAS allowed us to sample the TeV gamma-ray fluxes and energy spectra with unprecedented accuracy where Mrk 421 was detected in each of the pointings. A total of 47.3 hrs of VERITAS and 96 hrs of Whipple 10m data were acquired between January 2006 and June 2008. We present the results of a study of the TeV gamma-ray energy spectra as a function of time, and for different flux levels. On May 2nd and 3rd, 2008, bright TeV gamma-ray flares were detected with fluxes reaching the level of 10 Crab. The TeV gamma-ray data were complemented with radio, optical, and X-ray observations, with flux variability found in all bands except for the radio waveband. The combination of the RXTE and Swift X-ray data reveal spectral hardening with increasing flux levels, often correlated with an increase of the source activity in TeV gamma-rays. Contemporaneous spectral energy distributions were generated for 18 nights, each of which are reasonably described by a one-zone SSC model., Comment: 30 pages, 12 figures, accepted by ApJ
Published: 2011
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47. Veritas observations of the tev binary ls i +61° 303 during 2008-2010

Author: A. McCann, R. Dickherber, S. Thibadeau, E. Aliu, Sinéad M. Griffin, Wystan Benbow, M. P. Connolly, Gareth Hughes, R. Guenette, M. Kertzman, Gernot Maier, D. B. Saxon, N. H. Park, S. P. Wakely, Daniel Gall, J. H. Buckley, A. N. Otte, Henric Krawczynski, Jamie Holder, M. J. Lang, L. Ciupik, S. Vincent, A. J.R. Weinstein, J. S. Perkins, M. Vivier, L. C. Reyes, A. Varlotta, Reshmi Mukherjee, J. E. Ward, G. H. Sembroski, R. A. Ong, Thomas Weisgarber, M. Pohl, P. Moriarty, Nicola Galante, B. Zitzer, Geza Gyuk, Pratik Majumdar, S. LeBohec, J. Grube, Manel Errando, David A. Williams, F. Krennrich, A. D. Falcone, S. M. Bradbury, Matthew R. Orr, K. Tsurusaki, D. B. Kieda, Lucy Fortson, J. P. Finley, M. Theiling, D. Staszak, Victor A. Acciari, K. Ragan, G. Demet Senturk, C. M. Hui, Wei Cui, T. C. Weekes, Amy Furniss, A. Cannon, G. H. Gillanders, S. Godambe, H. J. Rose, H. Prokoph, V. V. Vassiliev, N. Karlsson, T. Aune, J. Ruppel, S. McArthur, V. Bugaev, Karen Byrum, G. Finnegan, A. W. Smith, C. Duke, M. Schroedter, E. Roache, A. Cesarini, G. Tešić, John L. Quinn, P. Kaaret, E. Collins-Hughes, T. B. Humensky, D. S. Hanna, T. C. Arlen, P. T. Reynolds, and Matthias Beilicke
Subjects: Astrophysics::High Energy Astrophysical Phenomena, ls-i-+61-303, FOS: Physical sciences, Proportional counter, Flux, Binary number, Astrophysics, orbital modulation, 01 natural sciences, law.invention, spectrum, Telescope, law, jet, 0103 physical sciences, MAGIC (telescope), microquasar, 010303 astronomy & astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, high-energy emission, 010308 nuclear & particles physics, Astronomy and Astrophysics, gamma rays: general, gamma-ray emission, radio, Orbit, Crab Nebula, binaries: general, x-ray, 13. Climate action, Space and Planetary Science, x-rays: binaries, Astrophysics - High Energy Astrophysical Phenomena, Fermi Gamma-ray Space Telescope
Abstract: We present the results of observations of the TeV binary LS I +61 303 with the VERITAS telescope array between 2008 and 2010, at energies above 300 GeV. In the past, both ground-based gamma-ray telescopes VERITAS and MAGIC have reported detections of TeV emission near the apastron phases of the binary orbit. The observations presented here show no strong evidence for TeV emission during these orbital phases; however, during observations taken in late 2010, significant emission was detected from the source close to the phase of superior conjunction (much closer to periastron passage) at a 5.6 standard deviation (5.6 sigma) post-trials significance. In total, between October 2008 and December 2010 a total exposure of 64.5 hours was accumulated with VERITAS on LS I +61 303, resulting in an excess at the 3.3 sigma significance level for constant emission over the entire integrated dataset. The flux upper limits derived for emission during the previously reliably active TeV phases (i.e. close to apastron) are less than 5% of the Crab Nebula flux in the same energy range. This result stands in apparent contrast to previous observations by both MAGIC and VERITAS which detected the source during these phases at >10% of the Crab Nebula flux. During the two year span of observations, a large amount of X-ray data were also accrued on LS I +61 303 by the Swift X-ray Telescope (XRT) and the Rossi X-ray Timing Explorer Timing (RXTE) Proportional Counter Array (PCA). We find no evidence for a correlation between emission in the X-ray and TeV regimes during 20 directly overlapping observations. We also comment on data obtained contemporaneously by the Fermi Large Area Telescope (LAT)., Accepted for Publication in The Astrophysical Journal, 21 pages, 3 tables, 6 figures
Published: 2011

48. Multiwavelength Observations of the very high energy Blazar 1ES2344+514

Author: L. Ciupik, E. Aliu, R. Dickherber, P. Kaaret, R. Guenette, B. Zitzer, J. E. Ward, Gernot Maier, S. P. Swordy, A. Varlotta, S. P. Wakely, D. Boltuch, A. N. Otte, D. S. Hanna, T. C. Arlen, A. Imran, Daniel Gall, Amanda Weinstein, A. Cannon, Thomas Brian Humensky, P. Cogan, M. Schroedter, Lucy Fortson, R. A. Ong, F. Krennrich, Matthew Wood, D. Pandel, Vladimir Vassiliev, Pierre Colin, S. LeBohec, J. S. Perkins, K. Ragan, M. Theiling, Henric Krawczynski, A. Konopelko, J. P. Finley, A. W. Smith, Amy Furniss, Reshmi Mukherjee, Matthias Beilicke, J. A. Toner, T. C. Weekes, Martin Pohl, G. H. Sembroski, A. D. Falcone, P. Moriarty, John Kildea, Stephanie Wissel, David Kieda, T. Weisgarber, J. Grube, Jamie Holder, P. T. Reynolds, Rick Wagner, S. Vincent, David A. Williams, C. M. Hui, Wystan Benbow, Geza Gyuk, V. Bugaev, V. A. Acciari, P. Fortin, H. J. Rose, S. J. Fegan, D. Steele, M. J. Lang, A. Pichel, T. Aune, N. Karlsson, John L. Quinn, D. Horan, M. Kertzman, and G. H. Gillanders
Subjects: Photon, Ciencias Físicas, bl-lacertae objects, Astrophysics, 01 natural sciences, Spectral line, law.invention, Telescope, purl.org/becyt/ford/1 [https], law, veritas, 0103 physical sciences, galaxies, strong flares, individual, Blazar, 010303 astronomy & astrophysics, Physics, markarian 501, 1ES 2344+514, 010308 nuclear & particles physics, spectral variability, Astronomy and Astrophysics, purl.org/becyt/ford/1.3 [https], gamma-ray emission, Galaxy, Massless particle, bl lacertae objects: individual (ies 2344+514), radiation, Astronomía, einstein slew survey, Crab Nebula, 13. Climate action, Space and Planetary Science, correlated variability, cherenkov telescopes, BL Lacertae objects, CIENCIAS NATURALES Y EXACTAS, Flare
Abstract: Multiwavelength observations of the high-frequency-peaked blazar 1ES 2344+514 were performed from October 2007 to January 2008. The campaign represents the first contemporanous data on the object at very high energy (VHE, E > 100 GeV) gamma-ray, X-ray, and UV energies. Observations with VERITAS in VHE gamma-rays yield a strong detection of 20 sigmas with 633 excess events in a total exposure of 18.1 hours live-time. A strong VHE gamma-ray flare on December 7, 2007 is measured at F(>300 GeV) = (6.76 ± 0.62) × 10^-11 cm^-2 s^-1 , corresponding to 48% of the Crab Nebula flux. Excluding this flaring episode, nightly variability at lower fluxes is observed with a time-averaged mean of F(>300 GeV) = (1.06 ± 0.09) × 10^-11 cm^-2 s^-1 (7.6% of the Crab Nebula flux). The differential photon spectrum between 390 GeV and 8.3 TeV for the time-averaged observations excluding December 7, 2007 is well described by a power law with a photon index of 2.78 ± 0.09 (stat) ± 0.15 (syst). A slightly harder photon index of 2.43 ± 0.22stat ± 0.15syst is measured on the flaring night of December 7, 2007. Over the full period of VERITAS observations contemporaneous X-ray and UV data were taken with Swift and RXTE. Variability by a factor of ~7 is evident in the 2-10 keV flux between nightly observations. On December 8, 2007 the highest ever observed X-ray flux from 1ES 2344+514 was measured by Swift XRT at a flux of F(2-10 keV) = (6.58 ± 0.37) × 10^-11 erg cm^-2 s^-1. Evidence for a correlation between the X-ray flux and VHE gamma-ray flux on nightly time-scales is indicated with a Pearson correlation coefficient of r = 0.60 ± 0.11. Contemporaneous spectral energy distributions (SEDs) of 1ES 2344+514 are presented for two distinct flux states. A one-zone synchrotron self-Compton (SSC) model describes both SEDs using parameters consistent with previous SSC modeling of 1ES 2344+514 from non-contemporaneous observations. Fil: Acciari, V. A.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos Fil: Aliu, E.. University of Delaware; Estados Unidos Fil: Arlen, T.. University of California; Estados Unidos Fil: Aune, T.. University of California; Estados Unidos Fil: Beilicke, M.. University of Washington; Estados Unidos Fil: Benbow, W.. Harvard-Smithsonian Center for Astrophysics; Estados Unidos Fil: Boltuch, D.. University of Delaware; Estados Unidos Fil: Bugaev, V.. University of Washington; Estados Unidos Fil: Cannon, A.. University College Dublin; Irlanda Fil: Ciupik, L.. Adler Planetarium and Astronomy Museum; Estados Unidos Fil: Cogan, P.. McGill University; Canadá Fil: Colin, P.. University of Utah; Estados Unidos Fil: Dickherber, R.. University of Washington; Estados Unidos Fil: Falcone, A.. University of Pennsylvania; Estados Unidos Fil: Fegan, S. J.. University of California; Estados Unidos Fil: Finley, J. P.. Purdue University; Estados Unidos Fil: Fortin, P.. Columbia University; Estados Unidos Fil: Fortson, L. F.. Adler Planetarium and Astronomy Museum; Estados Unidos Fil: Furniss, A.. University of California; Estados Unidos Fil: Gall, D.. Purdue University; Estados Unidos Fil: Gillanders, G. H.. National University of Ireland; Irlanda Fil: Grube, J.. University College Dublin; Irlanda Fil: Guenette, R.. McGill University; Canadá Fil: Gyup, G.. Adler Planetarium and Astronomy Museum; Estados Unidos Fil: Hanna, D.. McGill University; Canadá Fil: Holder, J.. University of Delaware; Estados Unidos Fil: Horan, D.. Ecole Polytechnique; Francia Fil: Hui, C. M.. University of Utah; Estados Unidos Fil: Humensky, T. B.. University Of Chicago; Estados Unidos Fil: Pichel, Ana Carolina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentina
Published: 2011
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49. Erratum: 'multi-wavelength observations of the flaring gamma-ray blazar 3c 66a in 2008 october' (2011, apj, 726, 43)

Author: Luca Baldini, Reshmi Mukherjee, Carla Buemi, I. de la Calle Perez, A. Varlotta, Wystan Benbow, Mn Mazziotta, Jamie Holder, J. P. Norris, A. Morselli, A. D. Falcone, V. Vitale, Henric Krawczynski, T. A. Porter, Takaaki Tanaka, J. Bregeon, P. Kaaret, Stefano Ciprini, David Sanchez, A. Bouvier, Keith Bechtol, J. M. Lopez, Stephen Fegan, P. D. Smith, J. Grube, A. Cannon, R. Turchetti, Manel Errando, Sang Hun Lee, Igor V. Moskalenko, D. Dumora, J. Mehault, T. Aune, J. Lande, J. E. Ward, F. Gargano, D. Pandel, T. Glanzman, P. Calcidese, S. M. Bradbury, A. Berduygin, Marco Ajello, Jun Kataoka, Olaf Reimer, Paul J. Wang, Mauro Dolci, T. Ylinen, D. Capezzali, Vladimir A. Hagen-Thorn, Seth Digel, H. Y. Hsiao, S. Buson, H. F.W. Sadrozinski, V. Bugaev, R. Bellazzini, V. A. Acciari, S. P. Swordy, J. Saino, G. Tešić, Steven Ritz, F. Piron, D. Parent, Vladimir Vassiliev, Luca Latronico, Julie McEnery, Benoit Lott, Anne Lähteenmäki, A. S. Johnson, S. Cutini, A. Konopelko, Joachim Ripken, Ekaterina Koptelova, Brian L Winer, Martin Pohl, Kari Nilsson, G. Tosti, P. L. Nolan, N. Gehrels, Uwe Bach, Corrado Trigilio, Wen Ping Chen, J. M. Casandjian, Geza Gyuk, S. Rainò, K. Ragan, A. McCann, Roger W. Romani, P. Moriarty, Gernot Maier, Karen Byrum, A. Chekhtman, Michele Fumagalli, D. Boltuch, Talvikki Hovatta, A. N. Otte, D. J. Suson, G. H. Sembroski, A. A. Moiseev, M. Pepe, M. G. Nikolashvili, A. Sievers, Ivan Agudo, D. Carosati, Deborah Dultzin, R. Dickherber, C. M. Raiteri, S. P. Wakely, D. Riquelme, Daniel Gall, Cullen H. Blake, M. Schroedter, R. A. Ong, B. Berenji, S. McArthur, Raúl Mújica, M. Razzano, T. L. Usher, Ryosuke Itoh, M. J. Lang, C. C. Cheung, M. Sorcia, D. da Rio, David S. Davis, G.L. Godfrey, J. F. Ormes, E. Do Couto E Silva, Lars Fuhrmann, E. Cavazzuti, Mark Gurwell, G. Umana, P. Spinelli, L. O. Takalo, Francesco Longo, Mar Roca-Sogorb, Claudia Cecchi, Hugh D. Aller, Atsushi Okumura, S. Thibadeau, Richard Dubois, L. A. Sigua, Elina Lindfors, J. S. Perkins, Melissa Pesce-Rollins, Markus Böttcher, A. C. Sadun, N. Karlsson, G. H. Gillanders, S. Godambe, David Hiriart, L. Ciupik, J. H. Panetta, C. Diltz, Merja Tornikoski, Tyrel J. Johnson, Tsunefumi Mizuno, Jason X. Prochaska, R. A. Cameron, Omer Celik, C. M. Hui, F. Loparco, W. N. Johnson, Charles D. Dermer, N. Galante, Diego F. Torres, E. Forné, S. LeBohec, Lucy Fortson, C. Monte, Rumen Bachev, Matthew Wood, M. Pasanen, M. McCutcheon, E. Charles, Jochen Heidt, S. Carrigan, Amy Furniss, P. Bruel, A. Tramacere, G. Demet Senturk, F. de Palma, H. Ungerechts, Stephan Wagner, G. Finnegan, A. W. Smith, Stefan Funk, O. M. Kurtanidze, M. Ziegler, José L. Gómez, Gloria Spandre, J. G. Thayer, A. Halkola, D. Hadasch, James Chiang, A. Sander, M. F. Aller, J. E. Grove, P. Roustazadeh, D. Horan, Roger Blandford, Zhenwei Yang, P. T. Reynolds, Hideaki Katagiri, E. Roache, Carmelo Sgrò, Riccardo Rando, Gianpiero Tagliaferri, E. Hays, David Kieda, Yasushi Fukazawa, David A. Williams, Amanda Weinstein, N. Vilchez, R. Guenette, Hiromitsu Takahashi, J. H. Buckley, M. Kertzman, R. Ligustri, Markus Ackermann, E. Nuss, M. S. Shaw, David Paneque, E. Aliu, P. Fortin, H. J. Rose, T. Kamae, M. Roth, M. Kuss, Erika Benítez, Emmanouil Angelakis, Jürgen Knödlseder, A. W. Borgland, Nicola Omodei, P. Fusco, F. Krennrich, Valeri M. Larionov, P. Lubrano, M. Hayashida, A. A. Abdo, E. Orlando, N. Palma, J. Ballet, A. Cesarini, D. Starr, Tatiana S. Konstantinova, G. N. Kimeridze, M. Theiling, I. Nestoras, S. Vincent, J. Dashti, Josh Bloom, Jan Conrad, S. Germani, R. Buehler, R. E. Hughes, F. Giordano, Alan P. Marscher, J. P. Finley, John L. Quinn, Luis C. Reyes, Peter F. Michelson, Marcello Giroletti, Emanuele Bonamente, A. Reimer, A. Pichel, P. Giommi, J. A. Ros, D. Steele, M. Ozaki, T. C. Weekes, D. J. Thompson, M. Hauser, Johann Cohen-Tanugi, R. Claus, A. Sillanää, M. S. Strickman, P. Beltrame, Tomaso Belloni, G. A. Caliandro, L. Guillemot, A. A. Arkharov, M. Naumann-Godo, A. P. Waite, Jeffrey D. Scargle, Marco Frailis, K. S. Wood, V. Vasileiou, D. Gasparrini, T. Ohsugi, Paolo Leto, M. Brigida, A. Brez, A. Di Paola, V. Pelassa, Nicola Giglietto, I. A. Grenier, D. S. Hanna, S. G. Jorstad, T. C. Arlen, A. Imran, L. Costamante, M. N. Lovellette, Stephanie Wissel, P. A. Caraveo, Persis S. Drell, Gudlaugur Johannesson, M. Villata, Michael Mommert, Justin Vandenbroucke, T. Weisgarber, Guido Barbiellini, Takeshi Nakamori, Thomas Brian Humensky, E. N. Kopatskaya, Matthias Beilicke, L. Tibaldo, Wei Cui, A. Makeev, M. E. Monzani, C. Favuzzi, Jodi Christiansen, J. B. Thayer, J. A. Zensus, S. Murgia, Denis Bastieri, and Sylvain Guiriec
Subjects: Physics, Space and Planetary Science, Gamma ray, Astronomy, Astronomy and Astrophysics, Multi wavelength, Astrophysics, Blazar
Published: 2011

50. Discovery of TeV Gamma Ray Emission from Tycho's Supernova Remnant

Author: S. McArthur, D. S. Hanna, P. Majumdar, J. E. Ward, V. A. Acciari, J. P. Finley, Philip Kaaret, A. S. Madhavan, Wystan Benbow, V. Bugaev, M. Kertzman, Gernot Maier, J. H. Buckley, T. C. Weekes, G. Tešić, M. J. Lang, E. Collins-Hughes, J. S. Perkins, S. P. Wakely, R. Dickherber, A. Cesarini, T. Aune, D. Gall, M. Beilicke, E. Aliu, S. Thibadeau, John L. Quinn, Henric Krawczynski, Karen Byrum, Geza Gyuk, Jamie Holder, G. Demet Senturk, H. J. Rose, A. Furniss, R. A. Ong, A. Varlotta, J. Grube, A. N. Otte, Frank Krennrich, M. Schroedter, Manel Errando, R. Guenette, M. Vivier, Reshmi Mukherjee, S. M. Bradbury, L. Ciupik, Vladimir Vassiliev, A. Cannon, C. M. Hui, S. Griffin, Stephan LeBohec, N. Karlsson, K. Tsurusaki, N. Galante, D. B. Saxon, David Kieda, David A. Williams, M. Theiling, N. H. Park, Patrick Slane, G. Finnegan, A. W. Smith, P. T. Reynolds, C. Duke, Lucy Fortson, Amanda Weinstein, Matthew Wood, G. H. Gillanders, P. Moriarty, S. Godambe, Dirk Pandel, M. Orr, Martin Pohl, K. Ragan, B. Zitzer, E. Roache, Thomas Brian Humensky, John P. Hughes, L. C. Reyes, A. McCann, Wei Cui, T. Weisgarber, S. Vincent, G. H. Sembroski, and T. C. Arlen
Subjects: catalog, Photon, shock acceleration, Point source, chandra, Astrophysics::High Energy Astrophysical Phenomena, Hadron, FOS: Physical sciences, Astrophysics, Type (model theory), 01 natural sciences, spectrum, expansion, 0103 physical sciences, Supernova remnant, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, High Energy Astrophysical Phenomena (astro-ph.HE), Physics, hess, 010308 nuclear & particles physics, turbulence, Gamma ray, Institut für Physik und Astronomie, Astronomy and Astrophysics, gamma rays: general, astronomy, galactic plane survey, Crab Nebula, Space and Planetary Science, ddc:520, High Energy Physics::Experiment, ism: individual objects (g120.1+01.4, tycho=ver j0025+641), constraints, Astrophysics - High Energy Astrophysical Phenomena, Energy (signal processing)
Abstract: We report the discovery of TeV gamma-ray emission from the Type Ia supernova remnant (SNR) G120.1+1.4, known as Tycho's supernova remnant. Observations performed in the period 2008-2010 with the VERITAS ground-based gamma-ray observatory reveal weak emission coming from the direction of the remnant, compatible with a point source located at $00^{\rm h} \ 25^{\rm m} \ 27.0^{\rm s},\ +64^{\circ} \ 10^{\prime} \ 50^{\prime\prime}$ (J2000). The TeV photon spectrum measured by VERITAS can be described with a power-law $dN/dE = C(E/3.42\;\textrm{TeV})^{-\Gamma}$ with $\Gamma = 1.95 \pm 0.51_{stat} \pm 0.30_{sys}$ and $C = (1.55 \pm 0.43_{stat} \pm 0.47_{sys}) \times 10^{-14}$ cm$^{-2}$s$^{-1}$TeV$^{-1}$. The integral flux above 1 TeV corresponds to $\sim 0.9%$ percent of the steady Crab Nebula emission above the same energy, making it one of the weakest sources yet detected in TeV gamma rays. We present both leptonic and hadronic models which can describe the data. The lowest magnetic field allowed in these models is $\sim 80 \mu$G, which may be interpreted as evidence for magnetic field amplification., Comment: 6 pages, 3 figures. Accepted in ApJL
Published: 2011
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