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AGILE is a γ-ray astrophysics space mission which will operate, starting from 2006, in the 30 MeV–50 GeV energy range with imaging capability also in the 15–45 keV energy band. In order to achieve the required detection sensitivity, all AGILE detectors are surrounded by an anticoincidence detector aimed at charged particle background rejection with an inefficiency as low as 10−4. In this work, the design and the structure of this anticoincidence detector are presented, as well as its performances in terms of charged particles detection inefficiency as derived from extensive calibrations performed at CERN PS.

SuperAGILE is the hard X-ray monitor of the AGILE gamma ray mission, in orbit since 23$^{rd}$ April 2007. It is an imaging experiment based on a set of four independent silicon strip detectors, equipped with one-dimensional coded masks, operating in the nominal energy range 18-60 keV. The main goal of SuperAGILE is the observation of cosmic sources simultaneously with the main gamma-ray AGILE experiment, the Gamma Ray Imaging Detector (GRID). Given its $\sim$steradian-wide field of view and its $\sim$15 mCrab day-sensitivity, SuperAGILE is also well suited for the long-term monitoring of Galactic compact objects and the detection of bright transients. The SuperAGILE detector properties and design allow for a 6 arcmin angular resolution in each of the two independent orthogonal projections of the celestial coordinates. Photon by photon data are continuously available by the experiment telemetry, and are used to derive images and fluxes of individual sources, with integration times depending on the source intensity and position in the field of view. In this paper we report on the main scientific results achieved by SuperAGILE over its first two years in orbit, until April 2009., Comment: Accepted for publication on Astronomy & Astrophysics

Galactic microquasars are binaries with a neutron star or stellar-mass black hole accreting gas from a companion star. They can accelerate particles to relativistic energies and emit radio flares, but the mechanism of jet energization is not known. A survey of the Cygnus region between mid-2007 and mid-2009 has detected four major γ-ray flaring episodes with energies over 100 MeV, each lasting 1 or 2 days, emanating from the microquasar Cygnus X-3. There is a clear pattern of temporal correlation between the γ-ray flares and transitional spectral states of radio and X-ray emission. Particle acceleration occurred a few days before radio jet ejections for two of the flares, suggesting that jet formation involves the production of highly energetic particles. Super-massive black holes in active galaxies can accelerate particles to relativistic energies, producing jets with associated γ-ray emission. Galactic 'microquasars' also produce relativistic jets; however, apart from an isolated event detected in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar. Here, a report of four γ-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 illuminates this important problem. Super-massive black holes in active galaxies can accelerate particles to relativistic energies1, producing jets with associated γ-ray emission. Galactic ‘microquasars’, which are binary systems consisting of a neutron star or stellar-mass black hole accreting gas from a companion star, also produce relativistic jets, generally together with radio flares2. Apart from an isolated event detected3 in Cygnus X-1, there has hitherto been no systematic evidence for the acceleration of particles to gigaelectronvolt or higher energies in a microquasar, with the consequence that we are as yet unsure about the mechanism of jet energization. Here we report four γ-ray flares with energies above 100 MeV from the microquasar Cygnus X-3 (an exceptional X-ray binary4,5,6 that sporadically produces radio jets7,8,9). There is a clear pattern of temporal correlations between the γ-ray flares and transitional spectral states of the radio-frequency and X-ray emission. Particle acceleration occurred a few days before radio-jet ejections for two of the four flares, meaning that the process of jet formation implies the production of very energetic particles. In Cygnus X-3, particle energies during the flares can be thousands of times higher than during quiescent states.

At INAF-Astronomical Observatory of Brera a study is under way to explore the problems related to the ion beam figuring of full scale Zerodur hexagonal mirrors of M1 for the European Extremely Large Telescope (E-ELT), having size of 1.4 m corner to corner. During this study it is initially foreseen the figuring of a scaled down version mirror of the same material having size of 1 m corner to corner to assess the relevant figuring problems and issues. This specific mirror has a radius of curvature of 3 m, which allows for easy interferometric measurement. A mechanical support was designed to minimize its deformations due to the gravity. The Ion Beam Figuring Facility used for this study has been recently completed in the Brera Observatory and has a figuring area of 140 cm x 170 cm. It employs a Kaufman ion source having 50 mm grids mounted on three axis. This system has been designed and developed to be autonomous and self-monitoring during the figuring process. The software and the mathematical tools used to compute the dwell time solution have been developed at INAF-OAB as well. Aim of this study is the estimation and optimization of the time requested to correct the surface adopting strategies to mitigate the well-known thermal problems related to the Zerodur material. In this paper, the results obtained figuring the 1 m corner-to-corner test segment are reported.

We perform an observational test on global oscillations in Be star circumstellar disks in the metal deficient environment of the SMC. According to the hybrid model of disk oscillations early-type Be stars require an optically thin line force to establish a density wave. The low metallicity in the SMC should therefore diminish or prevent the formation of disk oscillations in early-type Be stars. We present short wavelength range spectra around H α of 48 Be stars in the young open cluster NGC 330 in the SMC. We find that the fraction of early-type Be stars in NGC 330 which host a global disk oscillation does not differ from the known fraction of Galactic field Be stars. This observational result is in contradiction to the theoretical prediction. We discuss several interpretations and propose a further observational test.

The AGILE Mission will explore the gamma-ray Universe with a very innovative instrument combining for the first time a gamma-ray imager (sensitive in the range 30 MeV - 50 GeV) and a hard X-ray imager (sensitive in the range 15-45 keV). An optimal angular resolution and a large field of view are obtained by the use of state-of-the-art Silicon detectors integrated in a very compact instrument. AGILE will be operational at the beginning of 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources, Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing.

AGILE is a Scientific Mission dedicated to high‐energy astrophysics supported by ASI with scientific participation of INAF and INFN. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV – 50 GeV and 15 – 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering ∼ 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3–50 MeV. The broadband detection of GRBs and the study of implications for particle acceleration and high energy emission are primary goals of th emission. AGILE can image GRBs with 2–3 arcminutes error boxes in the hard X‐ray range, and provide broadband photon‐by photon detection in the 15–45 keV, 03–50 MeV, and 30 MeV–30 GeV energy ranges. Microsecond on‐board photon tagging and a ∼ 100 microsecond gamma‐ray detection deadtime will be crucial for fast GRB timing. On‐board calculated GRB coordinates and energy fluxes will be quickly transmitted to the ground by an ORBCOMM transceiver. AGILE have recently (December 2005) completed its gamma‐ray calibration. It is now (January 2006) undergoing satellite integration and testing. The PLSV launch is planned in early 2006. AGILE is then foreseen to be fully operational during the summer of 2006. It will be the only mission entirely dedicated to high‐energy astrophysics above 30 MeV during the period mid‐2006/mid‐2007.

We have produced a prototype broadband, low-sidelobe conical corrugated feed horn suitable for measurements of the Cosmic Microwave Blackground (CMB) radiation in the frequency band 120–150 GHz. The antenna is a first prototype for the Low Frequency Instrument array in ESA's PLANCK mission, a space project dedicated to CMB anisotropy mesurements in the 30–900 GHz range. We describe the fabrication method, based on silver electro-formation, and present the two-dimensional antenna beam pattern measured at 140 GHz with a milimeter-wave automated scalar test range. The beam has good symmetry in the E and H planes with a far sidelobe level approaching –60 dB at angles ∼ 80°. An upper limit to the return loss was measured to be –21 dB.

The implementation of a X-ray mission with high imaging capabilities, similar to those achieved with Chandra (< 1 arcsec Half Energy Width, HEW), but with a much larger throughput is a very attractive perspective, even if challenging. For such a mission the scientific opportunities, in particular for the study of the early Universe, would remain at the state of the art for the next decades. At the beginning of the new millennium the XEUS mission has been proposed, with an effective area of several m2 and an angular resolution better than 2 arcsec HEW. Unfortunately, after the initial study, this mission was not implemented, mainly due to the costs and the low level of technology readiness. Currently the most advanced proposal for such a kind of mission is the SMART-X project, led by CfA and involving several other US Institutes. This project is based on adjustable segments of thin foil mirrors with piezo-electric actuators, aiming to achieve an effective area < 2 m2 at 1 keV and an angular resolution better than 1 arcsec HEW. Another attractive technology to realize an X-ray telescope with similar characteristics is being developed at NASA/Goddard. In this case the mirrors are based on Si substrates that are super-polished and figured starting from a bulky Si ingot, from which they are properly cut. Here we propose an alternative method based on precise direct grinding, figuring and polishing of thin (a few mm) glass shells with innovative deterministic polishing methods. This is followed by a final correction via ion figuring to obtain the desired accuracy in order to achieve the 1 arc sec HEW requirement. For this purpose, a temporary stiffening structure is used to support the shell from the polishing operations up to its integration in the telescope supporting structure. We will present the technological process under development, the results achieved so far and some mission scenarios based on this kind of optics, aiming to achieve an effective area more than 10 times larger than Chandra and an angular resolution of 1 arcsec HEW on axis and of a few arcsec off-axis across a large field of view (1 deg in diameter).

One of the most difficult requests to be accomplished from the technological point of view for next generation x-ray telescopes is to combine high angular resolution and effective area. A significant increase of effective area can be reached with high precision but at the same time thin (2-3 mm thickness for mirror diameters of 30-110 cm) glass mirror shells. In the last few years the Brera Observatory has lead a development program for realizing this kind of monolithic thin glass shell. The fused silica has been chosen as shell substrate due to its thermal and mechanical properties. To bring the mirror shells to the needed accuracy, we have adopted a deterministic direct polishing method (already used for past missions as Einstein, Rosat, Chandra) to ten time thinner shells. The technological challenge has been solved using a temporary stiffening structure that allows the handling and the machining of so thin glass shells. The results obtained with a prototype shell at an intermediate stage of its development (17’’ HEW measured in full illumination mode with x-ray) indicate that the working concept is feasible and can be further exploited using the very large Ion Beam Facility available in our labs for the final high accuracy figuring of the thin shells. In this paper we present the required tolerances for the shell realization, the shells production chain flow and the ion beam facility up grading. Forecast on figuring time and expected performances of the figuring will also be given on the basis on the metrological data collected during past shell development.

The next generation wide-field X-ray telescope (WFXT) will require an angular resolution of ~5-10 arcsec almost constant across a wide field of view (~1 deg2 diameter). To achieve this goal, the design of the optical system has to be based on mirrors characterized by short length and polynomial profiles, as well as focal plane curvature and plate scale corrections. These concepts guarantee an improved angular resolution at large off-axis angle with respect to the normally used Wolter-I configuration. These telescopes are therefore optimal for survey purposes. A significant increase of effective area and grasp with respect to previous missions must also be achieved. This is possible with high precision but at the same time thin (2-3 mm thickness for mirror diameters of 30-110 cm) glass mirror shells. To achieve the goal of 5 arcsec and improve further the technology, we are considering different materials. Fused silica, a well-known material with good thermo-mechanical and polishability characteristics provide the best choice. To bring the mirror shells to the needed accuracy, we are adopting a deterministic direct polishing method (already used for past missions as Einstein, Rosat, Chandra). The technological challenge now is to apply it for almost ten times thinner shells.

The Wide Field X-ray Telescope (WFXT) is a medium class mission for X-ray surveys of the sky with an unprecedented area and sensitivity. In order to meet the effective area requirement, the design of the optical system is based on very thin mirror shells, with thicknesses in the 1-2 mm range. In order to get the desired angular resolution (10 arcsec requirement, 5 arcsec goal) across the entire 1x1 degree FOV (Field Of View), the design of the optical system is based on nested modified grazing incidence Wolter-I mirrors realized with polynomial profiles, focal plane curvature and plate scale corrections. This design guarantees an increased angular resolution at large off-axis angle with respect to the normally used Wolter I configuration, making WFXT ideal for survey purposes. The WFXT X-ray Telescope Assembly is composed by three identical mirror modules of 78 nested shells each, with diameter up to 1.1 m. The epoxy replication process with SiC shells has already been proved to be a valuable technology to meet the angular resolution requirement of 10 arcsec. To further mature the telescope manufacturing technology and to achieve the goal of 5 arcsec, a deterministic direct polishing method is under investigation. The direct polishing method has already been used for past missions (as Einstein, Rosat, Chandra): the technological challenge now is to apply it for almost ten times thinner shells. Under investigation is quartz glass (fused silica), a well-known material with good thermo-mechanical and polishability characteristics that could meet our goal in terms of mass and stiffness, with significant cost and time saving with respect to SiC. Our approach is based on two main steps: first quartz glass tubes available on the market are grinded to conical profiles, and second the obtained shells are polished to the required polynomial profiles by CNC (Computer Numerical Control) polishing machine. In this paper, the first results of the direct grinding and polishing of prototypes shells made by quartz glass with low thickness, representative of the WFXT optical design, are presented.

The AGILE Satellite [8] [9], launched the 23rd April 2007, is an italian mission devoted to high energy gamma‐ray astrophysics in the 30 MeV–50 GeV range, with a window in the hard‐X domain 18–60 keV. One of the on‐board detectors, the Mini‐Calorimeter (MCAL), was also designed to work as all sky transient monitor in the energy range 0.33–100 MeV. Though the main purpose of MCAL is the detection of cosmological Gamma‐Ray‐Bursts (GRB), MCAL detected transient events with a very brief duration, few msec, that does not match timing and spectral features of known cosmic GRB. These events more likely agree with the features of typical Terrestrial Gamma‐Ray Flashes as described in the literature and previously detected by the BATSE instrument onboard the Compton Gamma Ray Observatory and the RHESSI satellite. The characteristics of the detected TGF candidate events, as well as their geographical distribution will be presented and discussed.

AGILE, an Italian Space Agency (ASI) mission dedicated to the exploration of the gamma-ray Universe, was successfully launched on April 23, 2007 from the Indian base of Sriharikota in an low-particle background equatorial orbit at 550 km height. AGILE gamma ray range cover the 30 MeV – 50 GeV band with its detectors combined together in the Gamma-Ray Imaging Detector (GRID). An X-ray imager (SuperAGILE) operates in the 18 – 60 keV band. Some of the payload instruments are also operated to detect transient X and gamma events with the main target being the Gamma Ray Burst in the SuperAGILE band and above 300 keV. The GRID instrument consists of a Silicon-Tungsten Tracker, a Caesium Iodide Mini-Calorimeter (MCAL), and a plastic-scintillator Anticoincidence system (ACS). The GRID achieves an angular resolution of about 15’ for bright sources with an unprecedented large field-of-view about 2.5 sr with a time resolution of few microsec and a very reduced dead-time (less than 200 microsec for a gamma detection). The hard X-ray imager (SuperAGILE) combines a tungsten coded mask with Si detector with a technology identical to the Si-Tracker. It is on top of the gamma-ray detector and has an optimal angular resolution (about 6 arcmin) with good sensitivity over about 1 sr field of view (10–15 mCrab on axis for a 1-day integration). The burst monitoring combines the data from SuperAGILE and from MCAL which operates independently with a specific operative mode from 300 keV up to several tens of MeV. All the detector operations are mastered by the Payload Data Handling Unit (PDHU) that includes several operation for data selection and background rejection. AGILE has very innovative scientific payload for what concern both its detectors and its operative mode. After more than one year of in orbit operation the in-flight performances of the instruments as well as the operation of the background reducing algorithm are presented and the main scientific results achieved are discussed.

The SIMBOL-X formation-flight X-ray mission will be operated by ASI and CNES in 2014, with a large participation of the French and Italian high energy astrophysics scientific community. Also German and US Institutions are contributing in the implementation of the scientific payload. Thanks to the formation-flight architecture, it will be possible to operate a long (20 m) focal length grazing incidence mirror module, formed by 100 confocal multilayer-coated Wolter I shells. This system will allow us to focus X-rays over a very broad energy band, from 0.5 keV up to 80 keV and beyond, with more than two orders of magnitude improvement in angular resolution (20 arcsec HEW) and sensitivity (0.5 µCrab on axis @30 keV) compared to non focusing detectors used so far. The X-ray mirrors will be realized by Ni electroforming replication, already successfully used for BeppoSAX, XMM-Newton, and JET-X/SWIFT; the thickness trend will be about two times less than for XMM, in order to save mass. Multilayer reflecting coatings will be implemented, in order to improve the reflectivity beyond 10 keV and to increase the field of view 812 arcmin at 30 keV). In this paper, the SIMBOL-X optics design, technology and implementation challenges will be discussed; it will be also reported on recent results obtained in the context of the SIMBOL-X optics development activities.

High-throughput X-ray optics are required for future X-ray astronomy missions. These optics are composed of a large number of nested confocal mirrors with very thin thickness in order to reduce the losses due to the obstruction of the mirrors wall and to keep the weight within acceptable values. The replica technique by electroforming the mirrors from mandrels provides a cost-effective solution for the manufacture of these X-ray optical systems. In the paper is reported the application of the electroforming process for the fabrication of the X-ray imaging concentrators for the SAX project and for the JET-X X-ray telescope. Moreover some considerations are given concerning a possible use of more elaborated electroforming processes for manufacturing light-weight large-aperture X-ray optics.

The AGILE Mission will explore the gamma‐ray Universe with a very innovative instrument combining for the first time a gamma‐ray imager and a hard X‐ray imager. AGILE will be operational at the beginning of 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma‐Ray Bursts, unidentified gamma‐ray sources, Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV – 50 GeV and 15 – 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view covering ∼ 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3–50 MeV. The broadband detection of GRBs and the study of implications for particle acceleration and high energy emission are primary goals of the mission. AGILE can image GRBs with 2–3 arcminute error boxes in the hard X‐ray range, and provide bro...

The Ni electroforming replication process has been used successfully by Beppo-SAX, JET-X/SWIFT, and XMM-Newton, to produce their gold-coated X-ray mirrors. The important feature of the technique is that, also with thin substrates, it is possible to achieve a good angular resolution, which is important for obtaining high signal-to-noise ratios in deep observations and imaging extended sources, while the assembly and integration of the monolithic shells is a relatively easy task. Two approaches can be used for the up grade of this technique also to the case of mirrors with multilayer coating, to be used in future hard X-ray missions: i) the direct replication of the mirror shell, after the deposition of the multilayer film on the master (mandrel) surface followed by the electroforming of the Ni walls, ii) the application of the multilayer film to the internal surface of Ni mirror shells, previously realized by replication. In this paper the last results achieved in Italy in the context of an activity aiming at the development of the former of the two methods will be presented and discussed.

AGILE is an ASI gamma-ray astrophysics space Mission which will operate in the 30 MeV - 50 GeV range with imaging capabilities also in the 10 - 40 keV range. Primary scientific goals include the study of AGNs, gamma-ray bursts, Galactic sources, unidentified gamma-ray sources, diffuse Galactic and extragalactic gamma-ray emission, high-precision timing studies, and Quantum Gravity testing. The AGILE scientific instrument is based on an innovative design of three detecting systems: (1) a Silicon Tracker, (2) a Mini-Calorimeter, and (3) an ultralight coded mask system with Si-detectors (Super-AGILE). AGILE is designed to provide: (1) excellent imaging in the energy bands 30 MeV-50 GeV (5-10 arcmin for intense sources) and 10-40 keV (1-3 arcmin); (2) optimal timing capabilities, with independent readout systems and minimal deadtimes for the Silicon Tracker, Super-AGILE and Mini-Calorimeter; (3) large field of view for the gamma-ray imaging detector (~3 sr) and Super-AGILE (~1 sr). AGILE will be the only Mission entirely dedicated to source detection above 30 MeV during the period 2004-2006.

The VIRMOS Consortium has the task to design and manufacture two spectrographs for ESO VLT, VIMOS (Visible Multi-Object Spectrograph) and NIRMOS (Near Infrared Multi-Object Spectrograph). This paper describes how the Mask Manufacturing Unit (MMU), which cuts the slit masks to be used with both instruments, meets the scientific requirements and manages the storage and the insertion of the masks into the instrument. The components and the software of the two main parts of the MMU, the Mask Manufacturing Machine and the Mask Handling System, are illustrated together with the mask material and with the slit properties. Slit positioning is accurate within 15 micron, equivalent to 0.03 arcsec on the sky, while the slit edge roughness has an rms on the order of 0.03 pixels on scales of a slit 5 arcsec long and of 0.01 pixels on the pixel scale (0.205 arcsec). The MMU has been successfully installed during July/August 2000 at the Paranal Observatory and is now operational for spectroscopic mask cutting, compliant with the requested specifications., Comment: Accepted for publication in PASP April 2001 PASP Latex preprint style, 31 pages including 9 figures (5 jpg2eps compressed)

The VIRMOS consortium of French and Italian Institutes is manufacturing 2 wide field imaging multi-object spectrographs for the European Southern Observatory Very Large Telescope, with emphasis on the ability to carry over spectroscopic surveys of large numbers of sources. The Visible Multi-Object Spectrograph, VIMOS, is covering the 0.37 to 1 micron wavelength domain, with a full field of view of 4 by 7 by 8 arcmin 2 in imaging and MOS mode. The Near IR Multi-Object Spectrograph, NIRMOS, is covering the 0.9 to 1.8 microns wavelength range, with afield of view 4 by 6 by 8 arcmin 2 in MOS mode. The spectral resolution for both instrument scan reach up to R equals 5000 for a 0.5 arcsec wide slit. Multi-slit masks are produced by a dedicated Mask Manufacturing Machine cutting through thin Invar sheets and capable of producing 4 slit masks approximately 300 by 300 mm each with approximately slits 5.7 mm long in less than one hour. Integral field spectroscopy is made possible in VIMOS by switching in the beam specially build masks fed by 6400 fibers coming form a 54 by 54 arcsec 2 integral field head with a 80 by 80 array of silica micro-lenses. NIRMOS has a similar IFS unit with a field of 30 by 30 arcmin 2 . These instruments are designed to offer very large multiplexing capabilities. In MOS mode, about 1000 objects can be observed simultaneously with VIMOS, with a S/N equals 10 obtained on galaxies with I equals 24 in one hour, and approximately 200 objects can be observed simultaneously with NIRMOS, with a S/N equals 10 obtained don galaxies with J equals 22, H equals 20.6 in 1h at R eq equals 200. We present here the status of VIMOS, currently under final integration, with expected first light in the summer 2000, together with the final design of NIRMOS presented at the Final Design Review. The VLT-VIRMOS deep redshift survey of more with the final design of NIRMOS presented at the Final Design Review. The VLT-VIRMOS deep redshift survey of more than 150000 galaxies over the redshift range 0 < z < 5 will be undertaken based on 120 guaranteed nights awarded to the project.

We present the current design of the VIsible Multi-Object Spectrograph (VIMOS) and the Near InfraRed Multi-Object Spectrograph (NIRMOS) for the European Southern Observatory Very Large Telescope. The basic scientific requirement is to conduct very deep redshift surveys of large quantities of objects, in a minimum number of nights. The technical specifications are to allow for a large multiplex gain over a wide field, and a high efficiency of the optical train, over the 0.37 to 1.8 micrometer domain. The baseline technical concept is built around 4 channels, covering 4 X 7 X 8 arcmin2 for VIMOS and 4 X 7 X 7 arcmin2 for NIRMOS. Each channel is an imaging spectrograph with a large field adaptation lens, a collimator, grisms or filters, and a F/1.8 camera, coupled to a 2048 X 4096 pixels CCD for VIMOS, and a 20482 HgCdTe Rockwell array for NIRMOS. The unique multiplex gain allows to obtain spectra of up to 840 object simultaneously with VIMOS, and up to 170 with NIRMOS (10 arcsec slits). An integral field spectroscopy mode with more than 6400 fibers coupled to micro-lenses will be available for VIMOS, covering a 1 X 1 arcmin2 field. The VLT-VIRMOS survey of more than 150,000 galaxies is planned down to magnitudes IAB equals 24, coupled to an ultra deep probe to IAB equals 26.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The scientific instrumentation onboard the Italian X-ray Astronomy Satellite SAX foresees four X-ray Mirror Units operating in the energy range 0.1 - 10 KeV with spatial resolution of 1 arcmin Half Power Radius. The Mirror Units are composed of thirty nested confocal and coaxial very thin double cone mirrors made by a nickel electroforming replica technique. The paper presents the X-ray characterization data obtained at the PANTER facility on the Flight Mirror Units.

The scientific instrumentation onboard the Italian X-ray astronomy satellite SAX foresees X- ray imaging Mirror Units (MU) operating in the energy range 0.1 - 10 KeV with spatial resolution of 1 arcmin HPR. The MU are composed of thirty nested confocal and coaxial very thin double cone mirrors, made by a nickel electroforming replica technique. The paper presents the results obtained with the Engineering Qualification Model of the MU, which are well within the scientific requirements.

A development model of the X-ray imaging concentrators designed for the Italian satellite for X-ray astronomy (SAX) was used to verify the thermomechanical and imaging properties of the optical system. The development model has a set of 29 mirrors (of the total of 30 mirrors of SAX), which are representative of the final mirrors except for the microroughness, which is about 3 nm instead of less than 1 nm. Results are presented of the optical system tests with low-energy X-ray beam (E = 0.27 KeV) and with visible light.

Part I of this paper [1] presented the theory, and practical basis, of a complete system for active control of optical quality, with particular application to large telescopes. Reference was made to an experimental verification using a thin model mirror of 1 m diameter. Part II now gives a complete account of these experiments which consisted essentially of two parts: the verification of the theoretical modal calibrations and their orthogonality in practice, and the application of the calibrations to achieve the active modal correction of the mirror. Both aspects of the experiment were successful, with a precision higher than expected. The residual errors left after final correction are, by definition, of a higher order than the five corrected low spatial frequency terms and are small. However, one residual term is dominant (fifth-order astigmatism) but this was omitted in the correction process as being probably too high a mode to appear in practice. A calibration for this term will be performed...

The aim of this paper is to describe the support system which has been realized for the 1 m ESO active optics experiment. This experiment has been conceived in order to verify on a smaller scale the concept of the active optics, which is foreseen for the ESO NTT 3.5 m telescope. This concept has been widely discussed in references (1) (2) (3).For the purpose of completeness we will briefly summarize here the basic concept of the experiment, while we will describe in detail the support system and the characterization of the force actuator.

We present a variability study of a sample of bright gamma-ray (30 MeV -- 50 GeV) sources. This sample is an extension of the first AGILE catalogue of gamma-ray sources (1AGL), obtained using the complete set of AGILE observations in pointing mode performed during a 2.3 year period from July 9, 2007 until October 30, 2009. The dataset of AGILE pointed observations covers a long time interval and its gamma-ray data archive is useful for monitoring studies of medium-to-high brightness gamma-ray sources. In the analysis reported here, we used data obtained with an improved event filter that covers a wider field of view, on a much larger (about 27.5 months) dataset, integrating data on observation block time scales, which mostly range from a few days to thirty days. The data processing resulted in a better characterized source list than 1AGL was, and includes 54 sources, 7 of which are new high galactic latitude (|BII| >= 5) sources, 8 are new sources on the galactic plane, and 20 sources from the previous catalogue with revised positions. Eight 1AGL sources (2 high-latitude and 6 on the galactic plane) were not detected in the final processing either because of low OB exposure and/or due to their position in complex galactic regions. We report the results in a catalogue of all the detections obtained in each single OB, including the variability results for each of these sources. In particular, we found that 12 sources out of 42 or 11 out of 53 are variable, depending on the variability index used, where 42 and 53 are the number of sources for which these indices could be calculated. Seven of the 11 variable sources are blazars, the others are Crab pulsar+nebula, LS I +61{\deg}303, Cyg X-3, and 1AGLR J2021+4030., Comment: 30 pages, 12 figures

CHARACTERIZATION OF THE MANDRELS USED TO PRODUCE REPLICATED PROTOTYPE MIRRORS FOR THEITALIAN X -RAY SATELLITE SAXG. Bonelli, G.Conti, E.MattainiCNR - Istituto Fisica Cosmica - Via Bassini 15 Milano - ItalyO. CitterioOsservatorio Astronomico Brera- Merate - Via E. Bianchi 46 - 22055 Merate - ItalyABSTRACTWe present the results obtained during the characterization of the mandrels used

The scientific instrumentation on board of the Italian Satellite for X-ray Astronomy (SAX), foresees X-ray concentrators operating in the energy range 0.1 - 10 KeV with a spatial resolution of the order of 1 arcmin. This paper presents a study for the optics of such concentrators, based on several confocal nested mirrors. To reduce the loss of collecting area due to the thickness of the optics, it is necessary to use very thin mirrors. To achieve this result, still maintaining good optical quality, and to allow the construction of several concentrators at an acceptable cost, we propose the use of a replica technique by electroforming the mirrors from masters. The expected characteristics of the double cone geometry mirrors, together with preliminary results obtained with prototypes of electro-formed optics are presented.

The replica technique by electroforming the mirrors from mandrels, has been chosen for the manufacture of the X-ray optics of the SAX imaging concentrators. This technique ia also emerging as a promising cost-effective process for the construction of the mirror shells for high throughput X-ray optics telescopes with angular resolution of tens of arcsac. A key point in this process is the manufacture of the mandrels (or masters) with the required specifications for the geometrical profile and surface finishing. Possible cost-effective solutions for the production of the mandrels are: 1) to achieve the required profile by diamond turning and to improve the surface finishing by means of a lacquer coating process or 2) to reach the correct geometrical shape with a conventional lathe or grinding machine and, after a moderate surface polishing, to coat it with a lacquer layer. This paper presents the results obtained during the verification of these approaches.

The scientific instrumentation onboard the Italian satellite for x-ray astronomy (SAX) foresees x-ray imaging concentrators operating in the 0.1-10-keV energy range with a spatial resolution of 1 min of arc. The optics is composed of thirty confocal-nested very thin double-cone mirrors. To achieve good optical quality and to allow the construction of several concentrators at an acceptable cost, a replica technique by electroforming the mirrors from masters is used. This paper presents the results obtained from a set of electroformed mirrors mounted on a concentrator prototype.

AGILE is an Italian Space Agency mission dedicated to the observation of the gamma-ray Universe. The AGILE very innovative instrumentation combines for the first time a gamma-ray imager (sensitive in the energy range 30 MeV - 50 GeV), a hard X-ray imager (sensitive in the range 18-60 keV) together with a Calorimeter (sensitive in the range 300 keV - 100 MeV) and an anticoincidence system. AGILE was successfully launched on April 23, 2007 from the Indian base of Sriharikota and was inserted in an equatorial orbit with a very low particle background. AGILE provides crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, pulsars, unidentified gamma-ray sources, Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. An optimal angular resolution (reaching 0.1-0.2 degrees in gamma-rays, 1-2 arcminutes in hard X-rays) and very large fields of view (2.5 sr and 1 sr, respectively) are obtained by the use of Silicon detectors integrated in a very compact instrument. The paper describes the AGILE Mission and its space and ground segments., 20 pages, 26 figures. submitted to Astron. & Astrophys