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The Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) program monitors 849 active galactic nuclei (AGN) both spectroscopically and photometrically. The photometric observations used in this work span over four years and provide an excellent baseline for variability studies of these objects. We present the photometric light curves from 2014 to 2017 obtained by the Steward Observatory's Bok telescope and the CFHT telescope with MegaCam. We provide details on the data acquisition and processing of the data from each telescope, the difference imaging photometry used to produce the light curves, and the calculation of a variability index to quantify each AGN's variability. We find that the Welch-Stetson J-index provides a useful characterization of AGN variability and can be used to select AGNs for further study., Comment: Accepted for publication in ApJS, 28 pages, 8 figures, 4 tables

We present a survey of extremely high-velocity outflows (EHVOs) in quasars, defined by speeds between 0.1c and 0.2c. This region of the parameter space has not been included in previous surveys, but it might present the biggest challenge for theoretical models and it might be a large contributor to feedback due to the outflows' potentially large kinetic power. Using the Sloan Digital Sky Survey, we find 40 quasar spectra with broad EHVO CIV absorption, 10 times more than the number of previously known cases. We characterize the EHVO absorption and find that in 26 cases, CIV is accompanied by NV and/or OVI absorption. We find that EHVO quasars lack HeII emission and have overall larger bolometric luminosities and black hole masses than those of their parent sample and BALQSOs, while we do not find significant differences in their Eddington ratios. We also report a trend toward larger black hole masses as the velocity of the outflowing gas increases in the BALQSOs in our sample. The overall larger Lbol and lack of HeII emission of EHVO quasars suggest that radiation is likely driving these outflows. We find a potential evolutionary effect as EHVO quasars seem to be more predominant at large redshifts. We estimate that the kinetic power of these outflows may be similar to or even larger than that of the outflows from BALQSOs as the velocity factor increases this parameter by 1-2.5 orders of magnitude. Further study of EHVO quasars will help improve our understanding of quasar physics., Comment: 26 pages, accepted for publication in the Astrophysical Journal

Explainable machine learning (ML) enables human learning from ML, human appeal of automated model decisions, regulatory compliance, and security audits of ML models. Explainable ML (i.e. explainable artificial intelligence or XAI) has been implemented in numerous open source and commercial packages and explainable ML is also an important, mandatory, or embedded aspect of commercial predictive modeling in industries like financial services. However, like many technologies, explainable ML can be misused, particularly as a faulty safeguard for harmful black-boxes, e.g. fairwashing or scaffolding, and for other malevolent purposes like stealing models and sensitive training data. To promote best-practice discussions for this already in-flight technology, this short text presents internal definitions and a few examples before covering the proposed guidelines. This text concludes with a seemingly natural argument for the use of interpretable models and explanatory, debugging, and disparate impact testing methods in life- or mission-critical ML systems., Comment: Errata and updates available here: https://github.com/jphall663/responsible_xai

Most bulge-dominated galaxies host black holes with masses that tightly correlate with the masses of their bulges. This may indicate that the black holes may regulate galaxy growth or vice versa, or that they may grow in lock-step. The quest to understand how, when, and where those black-holes formed motivates much of extragalactic astronomy. Here we focus on a population of galaxies with active black holes in their nuclei (active galactic nuclei or AGN), that are fully or partially hidden by dust and gas: the emission from the broad line region is either completely or partially obscured with a visual extinction of 1 or above. This limit, though not yet precise, appears to be the point at which the populations of AGN may evolve differently. We highlight the importance of finding and studying those dusty AGN at redshifts between 1 and 3, the epoch when the universe may have gone through its most dramatic changes. We emphasize the need for future large multiplexed spectroscopic instruments that can perform dedicated surveys in the optical and NIR to pin down the demographics of such objects and study their reddening properties, star-formation histories, and excitation conditions. These key studies will shed light on the role of black holes in galaxy evolution during the epoch of peak growth activity., Comment: Science White Paper for the US Astro 2020 Decadal Survey, 5 pages, 2 figures

We present the results of the Extremely Luminous Quasar Survey in the $3\pi$ survey of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS; PS1). This effort applies the successful quasar selection strategy of the Extremely Luminous Survey in the Sloan Digital Sky Survey footprint ($\sim12,000\,\rm{deg}^2$) to a much larger area ($\sim\rm{21486}\,\rm{deg}^2$). This spectroscopic survey targets the most luminous quasars ($M_{1450}\le-26.5$; $m_{i}\le18.5$) at intermediate redshifts ($z\ge2.8$). Candidates are selected based on a near-infrared JKW2 color cut using WISE AllWISE and 2MASS photometry to mainly reject stellar contaminants. Photometric redshifts ($z_{\rm{reg}}$) and star-quasar classifications for each candidate are calculated from near-infrared and optical photometry using the supervised machine learning technique random forests. We select 806 quasar candidates at $z_{\rm{reg}}\ge2.8$ from a parent sample of 74318 sources. After exclusion of known sources and rejection of candidates with unreliable photometry, we have taken optical identification spectra for 290 of our 334 good PS-ELQS candidates. We report the discovery of 190 new $z\ge2.8$ quasars and an additional 28 quasars at lower redshifts. A total of 44 good PS-ELQS candidates remain unobserved. Including all known quasars at $z\ge2.8$, our quasar selection method has a selection efficiency of at least $77\%$. At lower declinations $-30\le\rm{Decl.}\le0$ we approximately triple the known population of extremely luminous quasars. We provide the PS-ELQS quasar catalog with a total of 592 luminous quasars ($m_{i}\le18.5$, $z\ge2.8$). This unique sample will not only be able to provide constraints on the volume density and quasar clustering of extremely luminous quasars, but also offers valuable targets for studies of the intergalactic medium., Comment: 34 pages, 10 figures, accepted to ApJS

(Abridged) The Maunakea Spectroscopic Explorer (MSE) is an end-to-end science platform for the design, execution and scientific exploitation of spectroscopic surveys. It will unveil the composition and dynamics of the faint Universe and impact nearly every field of astrophysics across all spatial scales, from individual stars to the largest scale structures in the Universe. Major pillars in the science program for MSE include (i) the ultimate Gaia follow-up facility for understanding the chemistry and dynamics of the distant Milky Way, including the outer disk and faint stellar halo at high spectral resolution (ii) galaxy formation and evolution at cosmic noon, via the type of revolutionary surveys that have occurred in the nearby Universe, but now conducted at the peak of the star formation history of the Universe (iii) derivation of the mass of the neutrino and insights into inflationary physics through a cosmological redshift survey that probes a large volume of the Universe with a high galaxy density. MSE is positioned to become a critical hub in the emerging international network of front-line astronomical facilities, with scientific capabilities that naturally complement and extend the scientific power of Gaia, the Large Synoptic Survey Telescope, the Square Kilometer Array, Euclid, WFIRST, the 30m telescopes and many more., Comment: 9 chapters, 301 pages, 100 figures. This version of the DSC is a comprehensive update of the original version, released in 2016, which can be downloaded at arXiv:1606.00043. A detailed summary of the design of MSE is available in the MSE Book 2018, available at arXiv:1810.08695

The ubiquitous variability of quasars across a wide range of wavelengths and timescales encodes critical information about the structure and dynamics of the circumnuclear emitting regions that are too small to be directly resolved, as well as detailed underlying physics of accretion and feedback processes in these active supermassive black holes. We emphasize the importance of studying quasar variability with time-domain spectroscopy, focusing on two science cases: (1) reverberation mapping (RM) to measure the broad-line region sizes and black hole masses in distant quasars; (2) spectroscopic follow-up of extreme variability quasars that dramatically change their continuum and broad-line flux within several years. We highlight the need for dedicated optical-infrared spectroscopic survey facilities in the coming decades to accompany wide-area time-domain imaging surveys, including: (1) the next phase of the Sloan Digital Sky Survey (SDSS-V; ~2020-2025), an all-sky, time-domain multi-object spectroscopic survey with 2.5m-class telescopes; (2) the planned Maunakea Spectroscopic Explorer, a dedicated 10m-class spectroscopic survey telescope with a 1.5 sq. deg field-of-view and multiplex of thousands of fibers in both optical and near-IR (J+H) to begin operations in 2029; (3) the Time-domain Spectroscopic Observatory (TSO), a proposed Probe-class ~1.3m telescope at L2, with imaging and spectroscopy (R=200, 1800) in 4 bands (0.3 - 5 micron) and rapid slew capability to 90% of sky, which will extend the coverage of Hbeta to z=8., Comment: Science White Paper for the US Astro 2020 Decadal Survey

(Abridged) This is the Maunakea Spectroscopic Explorer 2018 book. It is intended as a concise reference guide to all aspects of the scientific and technical design of MSE, for the international astronomy and engineering communities, and related agencies. The current version is a status report of MSE's science goals and their practical implementation, following the System Conceptual Design Review, held in January 2018. MSE is a planned 10-m class, wide-field, optical and near-infrared facility, designed to enable transformative science, while filling a critical missing gap in the emerging international network of large-scale astronomical facilities. MSE is completely dedicated to multi-object spectroscopy of samples of between thousands and millions of astrophysical objects. It will lead the world in this arena, due to its unique design capabilities: it will boast a large (11.25 m) aperture and wide (1.52 sq. degree) field of view; it will have the capabilities to observe at a wide range of spectral resolutions, from R2500 to R40,000, with massive multiplexing (4332 spectra per exposure, with all spectral resolutions available at all times), and an on-target observing efficiency of more than 80%. MSE will unveil the composition and dynamics of the faint Universe and is designed to excel at precision studies of faint astrophysical phenomena. It will also provide critical follow-up for multi-wavelength imaging surveys, such as those of the Large Synoptic Survey Telescope, Gaia, Euclid, the Wide Field Infrared Survey Telescope, the Square Kilometre Array, and the Next Generation Very Large Array., Comment: 5 chapters, 160 pages, 107 figures

This text discusses several popular explanatory methods that go beyond the error measurements and plots traditionally used to assess machine learning models. Some of the explanatory methods are accepted tools of the trade while others are rigorously derived and backed by long-standing theory. The methods, decision tree surrogate models, individual conditional expectation (ICE) plots, local interpretable model-agnostic explanations (LIME), partial dependence plots, and Shapley explanations, vary in terms of scope, fidelity, and suitable application domain. Along with descriptions of these methods, this text presents real-world usage recommendations supported by a use case and public, in-depth software examples for reproducibility., Comment: This manuscript is a preprint of the text for an invited talk at the 2019 KDD XAI workshop. A previous version has also appeared in the proceedings of the Joint Statistical Meetings. Errata and updates available here: https://github.com/jphall663/kdd_2019. Version 2 incorporated reviewer feedback. Version 3 includes a minor adjustment to Figure 1. Version 4 corrects a minor typo

We present a detailed characterization of the 849 broad-line quasars from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. Our quasar sample covers a redshift range of 0.1

The Maunakea Spectroscopic Explorer (MSE) will each year obtain millions of spectra in the optical to near-infrared, at low (R~3000) to high (R~40000) spectral resolution by observing >3000 spectra per pointing via a highly multiplexed fiber-fed system. Key science programs for MSE include black hole reverberation mapping, stellar population analysis of faint galaxies at high redshift, and sub-km/s velocity accuracy for stellar astrophysics. The architecture of MSE is an assembly of subsystems designed to meet the science requirements and describes what MSE will look like. In this paper we focus on the operations concept of MSE, which describes how to operate a fiber fed, highly multiplexed, dedicated observatory given its architecture and the science requirements. The operations concept details the phases of operations, from selecting proposals within the science community to distributing back millions of spectra to this community. For each phase, the operations concept describes the tools required to support the science community in their analyses and the operations staff in their work. It also highlights the specific needs related to the complexity of MSE with millions of targets to observe, thousands of fibers to position, and different spectral resolution to use. Finally, the operations concept shows how the science requirements on calibration and observing efficiency can be met., Comment: Proceedings of SPIE Astronomical Telescopes + Instrumentation 2018; Observatory Operations: Strategies, Processes, and Systems VII

We present the results of an automated fibre optic test bench constructed at the University of Victoria as part of the Maunakea Spectroscopic Explorer (MSE) Fibre Transmission System (FiTS). In preparation for MSE-FiTS, we have begun characterizing the focal ratio degradation (FRD) of candidate multi-mode fibres with the ultimate goal of testing all ~4000 MSE fibres. To achieve this, we have built an optical bench to perform an automated version of the collimated beam test. Herein we present the design of the bench and discuss the automation of components by introducing the Big FiTS Fibre Wrapper (Big FFW), our open-source automation software. We conclude with the results of tests performed using the Big FFW on a sample of candidate fibre, comparing the Big FFW results against those found using manual methods. Our results suggest that the candidate MSE fibre meets the science requirement of < 5% FRD at f=2 and less than 1% disagreement between both measurement methods., Comment: Proceedings of SPIE Astronomical Telescopes + Instrumentation 2018; Ground-based and Airborne Instrumentation for Astronomy VII

We isolate a set of quasars that exhibit emergent C iv broad absorption lines (BALs) in their spectra by comparing spectra in the SDSS Data Release 7 and the SDSS/BOSS Data Releases 9 and 10. After visually defining a set of emergent BALs, follow-up observations were obtained with the Gemini Observatory for 105 quasars. We find an emergence rate consistent with the previously reported disappearance rate of BAL quasars given the relative numbers of non-BAL and BAL quasars in the SDSS. We find candidate newly emerged BALs are preferentially drawn from among BALs with smaller balnicity indices, shallower depths, larger velocities, and smaller widths. Within two rest-frame years (average) after a BAL has emerged, we find it equally likely to continue increasing in equivalent width in an observation six months later (average) as it is to start decreasing. From the time separations between our observations, we conclude the coherence time-scale of BALs is less than 100 rest-frame days. We observe coordinated variability among pairs of troughs in the same quasar, likely due to clouds at different velocities responding to the same changes in ionizing flux; and the coordination is stronger if the velocity separation between the two troughs is smaller. We speculate the latter effect may be due to clouds having on average lower densities at higher velocities due to mass conservation in an accelerating flow, causing the absorbing gas in those clouds to respond on different timescales to the same ionizing flux variations., Comment: 37 pages, 25 figures

We present the rest-frame UV and optical photometry and morphology of low-redshift broad-line quasar host galaxies from the Sloan Digital Sky Survey Reverberation Mapping project. Our sample consists of 103 quasars at $z<0.8$, spanning a luminosity range of $-25\le M_g\le -17$ mag. We stack the multi-epoch images in the $g$ and $i$ bands taken by the Canada-France-Hawaii Telescope. The combined $g$-band ($i$-band) images reach a $5\sigma$ depth of 26.2 (25.2) mag, with a typical PSF size of $0.7"$ ($0.6"$). Each quasar is decomposed into a PSF and a S\'ersic profile, representing the central AGN and the host galaxy components, respectively. The systematic errors of the measured host galaxy flux in the two bands are 0.23 and 0.18 mag. The relative errors of the measured galaxy half-light radii ($R_e$) are about 13%. We estimate the rest-frame $u$- and $g$-band flux of the host galaxies, and find that the AGN-to-galaxy flux ratios in the $g$ band are between 0.9 to 4.4 (68.3% confidence). These galaxies have high stellar masses $M_\ast = 10^{10}\sim10^{11}\, M_\odot$. They have similar color with star-forming galaxies at similar redshifts, in consistent with AGN positive feedback in these quasars. We find that the $M_*-M_\text{BH}$ relation in our sample is shallower than the local $M_\text{Bulge}-M_\text{BH}$ relation. The S\'ersic indices and the $M_*-R_e$ relation indicate that the majority of the host galaxies are disk-like., Comment: 21 pages, 20 figures, accepted by ApJ

We report the discovery of 31 new redshifted broad absorption line quasars (RSBALs) from the Sloan Digital Sky Survey (SDSS). The number of previously known such objects is 19. The identification of the new objects was enabled by calculating similarities between quasar spectra in the SDSS. Using these similarities we look for the objects that are similar to the ones in the original sample, visually inspecting only hundreds, out of over 160,000 spectra considered. We compare the performance of several similarity measures, as well as different methods of employing them, in finding the RSBALs. We find that decision tree based similarities recover the most objects, and that an ensemble of methods performs better than any single one. As the similarities are not tailored for the specific problem of finding RSBALs, they could be used for searching for other types of quasars. The similarities and the code for their calculation are available online., Comment: Submitted to MNRAS. Comments are welcome!

Low-dose Proton Computed Tomography (pCT) is an evolving imaging modality that is used in proton therapy planning which addresses the range uncertainty problem. The goal of pCT is generating a 3D map of Relative Stopping Power (RSP) measurements with high accuracy within clinically required time frames. Generating accurate RSP values within the shortest amount of time is considered a key goal when developing a pCT software. The existing pCT softwares have successfully met this time frame and even succeeded this time goal, but requiring clusters with hundreds of processors. This paper describes a novel reconstruction technique using two Graphics Processing Unit (GPU) cores, such as is available on a single Nvidia P100. The proposed reconstruction technique is tested on both simulated and experimental datasets and on two different systems namely Nvidia K40 and P100 GPUs from IBM and Cray. The experimental results demonstrate that our proposed reconstruction method meets both the timing and accuracy with the benefit of having reasonable cost, and efficient use of power., Comment: IEEE NSS/MIC 2017

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V., Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected)

As astronomers increasingly exploit the information available in the time domain, spectroscopic variability in particular opens broad new channels of investigation. Here we describe the selection algorithms for all targets intended for repeat spectroscopy in the Time Domain Spectroscopic Survey (TDSS), part of the extended Baryon Oscillation Spectroscopic Survey within the Sloan Digital Sky Survey-IV. Also discussed are the scientific rationale and technical constraints leading to these target selections. The TDSS includes a large "Repeat Quasar Spectroscopy" (RQS) program delivering ~13,000 repeat spectra of confirmed SDSS quasars, and several smaller "Few-Epoch Spectroscopy" (FES) programs targeting specific classes of quasars as well as stars. The RQS program aims to provide a large and diverse quasar data set for studying variations in quasar spectra on timescales of years, a comparison sample for the FES quasar programs, and opportunity for discovering rare, serendipitous events. The FES programs cover a wide variety of phenomena in both quasars and stars. Quasar FES programs target broad absorption line quasars, high signal-to-noise ratio normal broad line quasars, quasars with double-peaked or very asymmetric broad emission line profiles, binary supermassive black hole candidates, and the most photometrically variable quasars. Strongly variable stars are also targeted for repeat spectroscopy, encompassing many types of eclipsing binary systems, and classical pulsators like RR Lyrae. Other stellar FES programs allow spectroscopic variability studies of active ultracool dwarf stars, dwarf carbon stars, and white dwarf/M dwarf spectroscopic binaries. We present example TDSS spectra and describe anticipated sample sizes and results., Comment: 26 pages, 11 figures, replaced with accepted version to AJ

If the atmospheric density $\rho_{atm}$ in the accretion disk of an active galactic nucleus (AGN) is sufficiently low, scattering in the atmosphere can produce a non-blackbody emergent spectrum. For a given bolometric luminosity, at ultraviolet and optical wavelengths such disks have lower fluxes and apparently larger sizes as compared to disks that emit as blackbodies. We show that models in which $\rho_{\rm atm}$ is a sufficiently low fixed fraction of the interior density $\rho$ can match the AGN STORM observations of NGC 5548 but produce disk spectral energy distributions that peak at shorter wavelengths than observed in luminous AGN in general. Thus, scattering atmospheres can contribute to the explanation for large inferred AGN accretion disk sizes but are unlikely to be the only contributor. In the appendix section, we present unified equations for the interior $\rho$ and $T$ in gas pressure-dominated regions of a thin accretion disk., Comment: 12 pages, 7 figures. ApJ accepted version. For \soundtrack information, see http://pathallresearch.blogspot.com/2017/11/soundtracks-in-aastex.html

The Astropy Project (http://astropy.org) is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages." For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community. Despite this, the project has always been and remains to this day effectively unfunded. Further, contributors receive little or no formal recognition for creating and supporting what is now critical software. This paper explores the problem in detail, outlines possible solutions to correct this, and presents a few suggestions on how to address the sustainability of general purpose astronomical software.

We present the Data Release 12 Quasar catalog (DR12Q) from the Baryon Oscillation Spectroscopic Survey (BOSS) of the SDSS-III. This catalog includes all SDSS-III/BOSS objects that were spectroscopically targeted as quasar candidates during the full survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities Mi[z=2]<-20.5 (in a LCDM cosmology with H_0 = 70 km/s/Mpc, Omega_M = 0.3, and Omega _L=0.7), and either display at least one emission line with a full width at half maximum (FWHM)larger than 500 km/s or, if not, have interesting/complex absorption features. The catalog also includes previously known quasars (mostly from SDSS-I and II) that were reobserved by BOSS. The catalog contains 297,301 quasars detected over 9,376 square degrees with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with z>2.15 is about an order of magnitude greater than the number of z>2.15 quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (CIV, CIII], MgII). The catalog identifies 29,580 broad absorption line quasars and lists their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry together with some information on the optical morphology and the selection criteria. When available, the catalog also provides information on the optical variability of quasars using SDSS and PTF multi-epoch photometry. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3,600-10,500A at a spectral resolution in the range 1,300

MSE is an 11.25m aperture observatory with a 1.5 square degree field of view that will be fully dedicated to multi-object spectroscopy. More than 3200 fibres will feed spectrographs operating at low (R ~ 2000 - 3500) and moderate (R ~ 6000) spectral resolution, and approximately 1000 fibers will feed spectrographs operating at high (R ~ 40000) resolution. MSE is designed to enable transformational science in areas as diverse as tomographic mapping of the interstellar and intergalactic media; the in-situ chemical tagging of thick disk and halo stars; connecting galaxies to their large scale structure; measuring the mass functions of cold dark matter sub-halos in galaxy and cluster-scale hosts; reverberation mapping of supermassive black holes in quasars; next generation cosmological surveys using redshift space distortions and peculiar velocities. MSE is an essential follow-up facility to current and next generations of multi-wavelength imaging surveys, including LSST, Gaia, Euclid, WFIRST, PLATO, and the SKA, and is designed to complement and go beyond the science goals of other planned and current spectroscopic capabilities like VISTA/4MOST, WHT/WEAVE, AAT/HERMES and Subaru/PFS. It is an ideal feeder facility for E-ELT, TMT and GMT, and provides the missing link between wide field imaging and small field precision astronomy. MSE is optimized for high throughput, high signal-to-noise observations of the faintest sources in the Universe with high quality calibration and stability being ensured through the dedicated operational mode of the observatory. (abridged), Comment: 210 pages, 91 figures. Exposure draft. Appendices to the Detailed Science Case can be found at http://mse.cfht.hawaii.edu/docs/

We study the dramatic decrease in iron absorption strength in the iron low-ionization broad absorption line quasar SDSS J084133.15+200525.8. We report on the continued weakening of absorption in the prototype of this class of variable broad absorption line quasar, FBQS J140806.2+305448. We also report a third example of this class, SDSS J123103.70+392903.6; unlike the other two examples, it has undergone an increase in observed continuum brightness (at 3000~\AA\ rest-frame) as well as a decrease in iron absorption strength. These changes could be caused by absorber transverse motion or by ionization variability. We note that the \mgii\ and UV \feii\ lines in several FeLoBAL quasars are blueshifted by thousands of \kms\ relative to the \Hb\ emission line peak. We suggest that such emission arises in the outflowing winds normally seen only in absorption., Comment: Accepted for publication in MNRAS. 15 pages, 16 figures

The surface gravity on Mars is smaller than the surface gravity on Earth, resulting in longer falling times. This effect can be simulated on Earth by taking advantage of air resistance and buoyancy, which cause low density objects to fall slowly enough to approximate objects falling on the surface of Mars. We describe a computer simulation based on an experiment that approximates Martian gravity, and verify our numerical results by performing the experiment., Comment: 2015 Phys. Educ. 50 643

Reverberation mapping (RM) measurements of broad-line region (BLR) lags in z>0.3 quasars are important for directly measuring black hole masses in these distant objects, but so far there have been limited attempts and success given the practical difficulties of RM in this regime. Here we report preliminary results of 15 BLR lag measurements from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project, a dedicated RM program with multi-object spectroscopy designed for RM over a wide redshift range. The lags are based on the 2014 spectroscopic light curves alone (32 epochs over 6 months) and focus on the Hbeta and MgII broad lines in the 100 lowest-redshift (z<0.8) quasars included in SDSS-RM; they represent a small subset of the lags that SDSS-RM (including 849 quasars to z~4.5) is expected to deliver. The reported preliminary lag measurements are for intermediate-luminosity quasars at 0.3<~z<0.8, including 9 Hbeta lags and 6 MgII lags, for the first time extending RM results to this redshift-luminosity regime and providing direct quasar black hole mass estimates over ~ half of cosmic time. The MgII lags also increase the number of known MgII lags by several-fold, and start to explore the utility of MgII for RM at high redshift. The location of these new lags at higher redshifts on the observed BLR size-luminosity relationship is statistically consistent with previous Hbeta results at z<0.3. However, an independent constraint on the relationship slope at z>0.3 is not yet possible due to the limitations in our current sample. Our results demonstrate the general feasibility and potential of multi-object RM for z>0.3 quasars., Comment: Replaced with the accepted version (ApJ); minor revisions in the presentation

We present the discovery of the highest velocity CIV broad absorption line to date in the z=2.47 quasar SDSS J023011.28+005913.6, hereafter J0230. In comparing the public DR7 and DR9 spectra of J0230, we discovered an emerging broad absorption trough outflowing at ~60,000 km/s, which we refer to as trough A. In pursuing follow up observations of trough A, we discovered a second emergent CIV broad absorption trough outflowing at ~40,000 km/s, namely trough B. In total, we collected seven spectral epochs of J0230 that demonstrate emergent and rapidly (~10 days in the rest-frame) varying broad absorption. We investigate two possible scenarios that could cause these rapid changes: bulk motion and ionization variability. Given our multi-epoch data, we were able to rule out some simple models of bulk motion, but have proposed two more realistic models to explain the variability of both troughs. Trough A is likely an augmented `crossing disk' scenario with the absorber moving at 10,000 < v (km/s) < 18,000. Trough B can be explained by a flow-tube feature travelling across the emitting region at 8,000 < v (km/s) < 56,000. If ionization variability is the cause for the changes observed, trough A's absorber has n_e >= 724 cm^-3 and is at r_{equal} >=2.00 kpc, or is at r < 2.00 kpc with no constraint on the density; trough B's absorber either has n_e >= 1540 cm^-3 and is at r_{equal} >= 1.37 kpc, or is at r < 1.37 kpc with no constraint on the density., Comment: 16 pages, 14 figures, 3 tables

We explore the variability of quasars in the MgII and Hbeta broad emission lines and UV/optical continuum emission using the Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM). This is the largest spectroscopic study of quasar variability to date: our study includes 29 spectroscopic epochs from SDSS-RM over $6$ months, containing 357 quasars with MgII and 41 quasars with Hbeta . On longer timescales, the study is also supplemented with two-epoch data from SDSS-I/II. The SDSS-I/II data include an additional $2854$ quasars with MgII and 572 quasars with Hbeta. The MgII emission line is significantly variable ($\Delta f/f$ 10% on 100-day timescales), a necessary prerequisite for its use for reverberation mapping studies. The data also confirm that continuum variability increases with timescale and decreases with luminosity, and the continuum light curves are consistent with a damped random-walk model on rest-frame timescales of $\gtrsim 5$ days. We compare the emission-line and continuum variability to investigate the structure of the broad-line region. Broad-line variability shows a shallower increase with timescale compared to the continuum emission, demonstrating that the broad-line transfer function is not a $\delta$-function. Hbeta is more variable than MgII (roughly by a factor of $1.5$), suggesting different excitation mechanisms, optical depths and/or geometrical configuration for each emission line. The ensemble spectroscopic variability measurements enabled by the SDSS-RM project have important consequences for future studies of reverberation mapping and black hole mass estimation of $1

The leading theory for the origin of the Moon is the giant impact hypothesis, in which the Moon was formed out of the debris left over from the collision of a Mars-sized body with the Earth. Soon after its formation, the orbit of the Moon may have been very different than it is today. We have simulated the phases of the Moon in a model for its formation wherein the Moon develops a highly elliptical orbit with its major axis tangential to the Earth's orbit. This note describes these simulations and their pedagogical value., Comment: 4 pages, 2 figures

The Sloan Digital Sky Survey Reverberation Mapping project (SDSS-RM) is a dedicated multi-object RM experiment that has spectroscopically monitored a sample of 849 broad-line quasars in a single 7 deg$^2$ field with the SDSS-III BOSS spectrograph. The RM quasar sample is flux-limited to i_psf=21.7 mag, and covers a redshift range of 0.10.3, and will investigate the prospects of RM with all major broad lines covered in optical spectroscopy. SDSS-RM will provide guidance on future multi-object RM campaigns on larger scales, and is aiming to deliver more than tens of BLR lag detections for a homogeneous sample of quasars. We describe the motivation, design and implementation of this program, and outline the science impact expected from the resulting data for RM and general quasar science., Comment: 25 pages, submitted to ApJS; project website at http://www.sdssrm.org

We present the Data Release 10 Quasar (DR10Q) catalog from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III. The catalog includes all BOSS objects that were targeted as quasar candidates during the first 2.5 years of the survey and that are confirmed as quasars via visual inspection of the spectra. The catalog also includes known quasars (mostly from SDSS-I and II) that were reobserved by BOSS. The catalog contains 166,583 quasars (74,454 are new discoveries since SDSS-DR9) detected over 6,373 deg$^{2}$ with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with $z>2.15$ (117,668) is $\sim$5 times greater than the number of $z>2.15$ quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (CIV, CIII, MgII). The catalog identifies 16,461 broad absorption line quasars and gives their characteristics. For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag and information on the optical morphology and selection method. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3,600-10,500\AA\ at a spectral resolution in the range 1,300$<$R$<$2,500; the spectra can be retrieved from the SDSS Catalog Archive Server. We also provide a supplemental list of an additional 2,376 quasars that have been identified among the galaxy targets of the SDSS-III/BOSS., Comment: Accepted for publication in A&A. The catalog is available at http://www.sdss3.org/dr10/algorithms/qso_catalog.php (Note that there is a slight delay for the website to appear online)

A previously unknown optical transient (OT 120926) has been observed in the constellation Bootes. The transient flared to magnitude 4.7, which is comparable to the visual magnitudes of the nearby stars $\pi$ Boo and $\omicron$ Boo. Database searches do not yield an unambiguous identification of a quiescent counterpart of this transient but do identify several candidates. However, none of the candidate stellar counterparts have shown any credible evidence of previous variability in the All-Sky Automated Survey or the Catalina Real-time Transient Survey. A flare on the nearby high proper motion, probable M dwarf star LP 440-48 could have produced OT 120926, but the amplitude of the flare would be an unprecedented 11.3 magnitudes. The current record amplitude for such flares on M dwarfs is 9.5 magnitudes., Comment: 12 pages, 5 figures, PDF only. JAAVSO in press. For further discussion, see http://pathallresearch.blogspot.ca/2013/11/looking-for-counterpart-of-naked-eye.html

We report the results of a new 60 ks Chandra X-ray Observatory Advanced CCD Imaging Spectrometer S-array (ACIS-S) observation of the reddened, radio-selected, highly polarized `FeLoBAL' quasar FIRST J1556+3517. We investigated a number of models of varied sophistication to fit the 531-photon spectrum. These models ranged from simple power laws to power laws absorbed by hydrogen gas in differing ionization states and degrees of partial covering. Preferred fits indicate that the intrinsic X-ray flux is consistent with that expected for quasars of similarly high luminosity, i.e., an intrinsic, dereddened and unabsorbed optical to X-ray spectral index of -1.7. We cannot tightly constrain the intrinsic X-ray power-law slope, but find indications that it is flat (photon index Gamma = 1.7 or flatter at a >99% confidence for a neutral hydrogen absorber model). Absorption is present, with a column density a few times 10^23 cm^-2, with both partially ionized models and partially covering neutral hydrogen models providing good fits. We present several lines of argument that suggest the fraction of X-ray emissions associated with the radio jet is not large. We combine our Chandra data with observations from the literature to construct the spectral energy distribution of FIRST J1556+3517 from radio to X-ray energies. We make corrections for Doppler beaming for the pole-on radio jet, optical dust reddening, and X-ray absorption, in order to recover a probable intrinsic spectrum. The quasar FIRST J1556+3517 seems to be an intrinsically normal radio-quiet quasar with a reddened optical/UV spectrum, a Doppler-boosted but intrinsically weak radio jet, and an X-ray absorber not dissimilar from that of other broad absorption line quasars., Comment: to be published in MNRAS

Microlensing observations indicate that quasar accretion discs have half-light radii larger than expected from standard theoretical predictions based on quasar fluxes or black hole masses. Blackburne and colleagues have also found a very weak wavelength dependence of these half-light radii. We consider disc temperature profile models that might match these observations. Nixon and colleagues have suggested that misaligned accretion discs around spinning black holes will be disrupted at radii small enough for the Lense-Thirring torque to overcome the disc's viscous torque. Gas in precessing annuli torn off a disc will spread radially and intersect with the remaining disc, heating the disc at potentially large radii. However, if the intersection occurs at an angle of more than a degree or so, highly supersonic collisions will shock-heat the gas to a Compton temperature of T~10^7 K, and the spectral energy distributions (SEDs) of discs with such shock-heated regions are poor fits to observations of quasar SEDs. Torn discs where heating occurs in intermittent weak shocks that occur whenever the intersection angle reaches a tenth of a degree pose less of a conflict with observations, but do not have significantly larger half-light radii than standard discs. We also study two phenomenological disc temperature profile models. We find that discs with a temperature spike at relatively large radii and lowered temperatures at radii inside the spike yield improved and acceptable fits to microlensing sizes in most cases. Such temperature profiles could in principle occur in sub-Keplerian discs partially supported by magnetic pressure. However, such discs overpredict the fluxes from quasars studied with microlensing except in the limit of negligible continuum emission from radii inside the temperature spike., Comment: Submitted to MNRAS. Comments welcome. 20 pages, 5 figures

We report the discovery in the Sloan Digital Sky Survey and the SDSS-III Baryon Oscillation Spectroscopic Survey of seventeen broad absorption line (BAL) quasars with high-ionization troughs that include absorption redshifted relative to the quasar rest frame. The redshifted troughs extend to velocities up to v=12,000 km/s and the trough widths exceed 3000 km/s in all but one case. Approximately 1 in 1000 BAL quasars with blueshifted C IV absorption also has redshifted C IV absorption; objects with C IV absorption present only at redshifted velocities are roughly four times rarer. In more than half of our objects, redshifted absorption is seen in C II or Al III as well as C IV, making low-ionization absorption at least ten times more common among BAL quasars with redshifted troughs than among standard BAL quasars. However, the C IV absorption equivalent widths in our objects are on average smaller than those of standard BAL quasars with low-ionization absorption. We consider several possible ways of generating redshifted absorption. The two most likely possibilities may be at work simultaneously, in the same objects or in different ones. Rotationally dominated outflows seen against a quasar's extended continuum source can produce redshifted and blueshifted absorption, but variability consistent with this scenario is seen in only one of the four objects with multiple spectra. The infall of relatively dense and low-ionization gas to radii as small as 400 Schwarzschild radii can in principle explain the observed range of trough profiles, but current models do not easily explain the origin and survival of such gas. Whatever the origin(s) of the absorbing gas in these objects, it must be located at small radii to explain its large redshifted velocities, and thus offers a novel probe of the inner regions of quasars., Comment: MNRAS in press. 40 pages, 17 figures (a few of reduced quality); for full-resolution figures see http://www.yorku.ca/phall/RESEARCH/rsub3-aas.pdf