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opencc-by-4.0Jun 2020View details →

SPECTRAL PROPERTIES OF QUASARS FROM SLOAN DIGITAL SKY SURVEY DATA RELEASE 14: THE CATALOG

We present measurements of the spectral properties for a total of 526,265 quasars, out of which 63% have continuum S/N> 3 pixel−1, selected from the fourteenth data release of the Sloan Digital Sky Survey (SDSS-DR14) quasar catalog. We performed a careful and homogeneous analysis of the SDSS spectra of these sources, to estimate the continuum and line properties of several emission lines such as Hα, Hβ, Hγ, Mg ii, C iii], C iv and Lyα. From the derived emission line parameters, we estimated single-epoch virial black hole masses (MBH) for the sample using Hβ, Mg ii, and C iv emission lines. The sample covers a wide range in bolometric luminosity (log Lbol; erg s−1 ) between 44.4 and 47.3 and log MBH between 7.1 and 9.9 M. Using the ratio of Lbol to the Eddington luminosity as a measure of the accretion rate, the logarithm of the accretion rate is found to be in the range between −2.06 and 0.43. We performed several correlation analyses between different emission line parameters and found them to match with that known earlier using smaller samples. We noticed that strong Fe ii sources with large Balmer line width, and highly accreting sources with large MBH are rare in our sample. We make available an extended and complete catalog that contains various spectral properties of 526,265 quasars derived in this work along with other properties culled from the SDSS-DR14 quasar catalog.   Here, you will find the entire spectral catalog in the FITS format. <ul> <li>The main catalog (“ dr14q_spec_prop.fits”) is based on the spectral information from this study consisting of 274 columns, which are described in Table B4.</li> <li>An extended catalog (“ dr14q_spec_prop_ext.fits”) where all the columns of DR14Q (Paris et al. 2018) are appended after the main catalog (ie, after column # 274). The extended catalog has a total of 380 columns.</li> </ul> We also make available all the model components (in FITS format) for each quasar and the spectral decomposition plots (PDF format): <a href="https://seafile.utu.fi/d/9866433c200743119e92/">HERE</a> <ul> <li>Each model FITS file has the following 8 columns:</li> </ul> <blockquote> <ol> <li>wave : rest-frame wavelength</li> <li>flux : rest-frame spectral flux</li> <li>err : rest-frame spectral flux uncertainty</li> <li>model_host : decomposed host-Galaxy flux</li> <li>model_pl_bc : a sum of the model power law and Balmer continuum</li> <li>model_feii : a sum of the Fe II UV and Fe II optical</li> <li>model_line_bc : total broad line model</li> <li>model_line_nc : total narrow line model</li> </ol> </blockquote> <ul> <li>A dedicated website has been created for Supplementary material:  <a href="http://www.utu.fi/sdssdr14">WEBSITE</a></li> </ul>

opencc-by-nc-4.0Dec 2015View details →

Testing sky brightness models against radial dependency: A dense two dimensional survey around the city of Madrid, Spain: SQM data

We present a study of the night sky brightness around the extended metropolitan area of Madrid using Sky Quality Meter (SQM) photometers. The map is the first to cover the spatial distribution of the sky brightness in the center of the Iberian peninsula. These surveys are neccessary to test the light pollution models that predict night sky brightness as a function of the location and brightness of the sources of light pollution and the scattering of light in the atmosphere. We describe the data-retrieval methodology, which includes an automated procedure to measure from a moving vehicle in order to speed up the data collection, providing a denser and wider survey than previous works with similar time frames. We compare the night sky brightness map to the nocturnal radiance measured from space by the DMSP satellite. We find that i) a single source model is not enough to explain the radial evolution of the night sky brightness, despite the predominance of Madrid in size and population, and ii) that the orography of the region should be taken into account when deriving geo-specific models from general first-principles models. We show the tight relationship between these two luminance measures. This finding sets up an alternative roadmap to extended studies over the globe that will not require the local deployment of photometers or trained personnel.

opencc-by-4.0Mar 2024View details →

Data referring to the Article "Harmonized Skies: A Survey on Drone Acceptance across Europe" published in Drones Journal

The material provided is part of the article "Harmonized Skies: A Survey on Drone Acceptance across Europe," published in the Drones Journal (https://doi.org/10.3390/drones8030107). This article describes a study investigating civil drone acceptance in six different EU countries. This study was part of the USpace4UAM project (Grant Agreement No 101017643). The material includes the data set for the study described and the Python codes for the random forest analysis carried out to investigate the influence of demographic and personnel factors on drone acceptance.

opencc-by-4.0Sep 2024View details →

MACADAMIA Sloan Digital Sky Survey Asteroid Photometry, Measurements, and Images

This dataset contains data from the Multi-Archive Catalog of Asteroid Detections And Measurements for Interactive Access (MACADAMIA), specifically of numbered asteroids observed serendipitously by the Sloan Digital Sky Survey (SDSS). photometry_archive_20201027.db is a SQLite database containing data corresponding to a search of the SDSS image archive conducted on 2020 May 1 of all numbered asteroids known at the time, which yielded 2.84 million search results, 1.98 million detections that were determined to actually be within the field of view of the identified image, and 993,777 successfully measured detections.  Preview images of all detections and non-detections where the object was determined to be within the field of view of an identified image are collected in the detection_previews_*tar.gz files in this dataset, indexed by detection_id in the photometry database and listed under preview_image_file in the detection_data table. photometry_archive_20210927.db contains an update to the SDSS search, containing data corresponding to a search of the SDSS image archive conducted on 2021 July 2 of all numbered asteroids known at the time, which yielded 2.96 million search results, 2.06 million detections that were determined to actually be within the field of view of the identified image, and 1.02 million successfully measured detections.  Previews of additional detections identified in this updated search may not be available due to data loss in a system failure in August 2023.

opencc-by-4.0Oct 2023View details →

Sky model from the paper "Prospects for a survey of the Galactic plane with the Cherenkov Telescope Array" by the CTA Consortium

The main source model definition file is provided in two formats. - models_gps.xml: readable using GammaLib/ctools, see http://cta.irap.omp.eu/ctools/users/user_manual/models.html - models_gps.yaml: readable using Gammapy, see https://docs.gammapy.org/1.1/tutorials/api/models.html#model-lists-and-serialisation   We provide separately the three alternative interstellar emission models. - base: IEM_base.fits - varmin: IEM_varmin.fits.gz - varmin-rescaled: IEM_varmin_rescaled.fits.gz To use the interstellar models one can employ: - GammaLib/ctools, see http://cta.irap.omp.eu/ctools/users/user_manual/models_spatial.html#diffusemapcube - Gammapy, see https://docs.gammapy.org/1.1/tutorials/data/fermi_lat.html#galactic-diffuse-background   This work was conducted in the context of the CTA Consortium. We gratefully acknowledge financial support from the agencies and organizations listed here: https://www.cta-observatory.org/consortium_acknowledgments/.

zenodo28/100

The Sloan Digital Sky Survey Reverberation Mapping Project: the XMM-Newton X-ray source catalog and multi-band counterparts

The XMM-RM project was designed to provide X-ray coverage of the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) field. 41 XMM-Newton exposures, placed surrounding the Chandra AEGIS field, were taken, covering an area of 6.13 deg2 and reaching a nominal exposure depth of &sim; 15 ks. We present an X-ray catalog of 3553 sources detected in these data, using a PSF-fitting algorithm and a sample selection threshold that produces a &sim; 5% fraction of spurious sources. The Bayesian method “NWAY” was employed to identify counterparts of the X-ray sources from the optical Legacy and the IR unWISE catalogs, using a 2-dimensional unWISE magnitude-color prior created from optical/IR counterparts of Chandra X-ray sources. 932 of the XMM-RM sources are covered by SDSS spectroscopic observations. 89% of them are classified as AGN, and 71% of these AGN are in the SDSS-RM quasar catalog. Among the SDSS-RM quasars, 80% are detectable at the depth of the XMM observations. Forced X-ray photometry is performed at the positions of the undetected SDSS-RM quasars.

opencc-by-4.0Aug 2020View details →

ROSAT All-Sky Survey Archival Data

This database table contains the list German ROSAT All-Sky Survey observations which were obtained during the ROSAT All-Sky Survey phase (1990 July 30 to 1991 Jan 25) and which have become available to the public. These data were obtained in scanning mode and therefore an individual dataset covers a much larger area of the sky than do pointed moded observations. In addition all these data were obtained with PSPC-C, while all pointed mode observations after the end of the All-Sky Survey were obtained with PSPC-B. For each observation listed in this database table, the instrument used, processing site, and coordinates of the field center are given, as well as the ROSAT observation request number (ROR), actual exposure time, date the observation took place, and more. For details about the ROSAT instruments, consult the ROSAT Mission Description (NASA Research Announcement for ROSAT, Appendix F and its addendum) and the ROSAT GSFC GOF website at <a href="http://heasarc.gsfc.nasa.gov/docs/rosat/rosgof.html">http://heasarc.gsfc.nasa.gov/docs/rosat/rosgof.html</a> for more information. For more information about the ROSAT All Sky Survey, see the ROSAT All Sky Survey page at <a href="http://www.xray.mpe.mpg.de/cgi-bin/rosat/rosat-survey">http://www.xray.mpe.mpg.de/cgi-bin/rosat/rosat-survey</a>. This database table was created at the HEASARC in March 2002, based on information provided by Max-Planck-Institut fuer extraterrestrische Physik at <a href="http://wave.xray.mpe.mpg.de/">http://wave.xray.mpe.mpg.de/</a>. This is a service provided by NASA HEASARC .

ROSAT All-Sky Survey Completely Identified Northern Sample

This table contains a completely identified sample of northern ROSAT All-Sky Survey (RASS) X-ray sources, as well as some additional X-ray sources which either had count rates below the adopted limits or were located outside the boundaries of the study areas. It is a catalog of optical identifications of a representative sample of northern (declination > -9 degrees) RASS sources. A full identification has been carried out for a count-rate- and area-limited complete RASS subsample comprising 674 sources. All sources are within six study areas outside the galactic plane (absolute galactic latitude |b| > 19.6 degrees), one area being near the North Galactic Pole and one near the North Ecliptic Pole. This table was created by the HEASARC in August 2003 based on CDS tables J/ApJS/117/319/table1.dat.gz and J/ApJS/117/319/table2.dat.gz. This is a service provided by NASA HEASARC .

Sloan Digital Sky Survey Quasars Detected by Chandra

The authors have studied the spectral energy distributions and evolution of a large sample of optically selected quasars from the Sloan Digital Sky Survey (SDSS) that were observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project (ChaMP). Their highest-confidence matched sample (which this HEASARC table comprises) includes 1135 X-ray detected quasars in the redshift range 0.2 < z < 5.4, representing some 36 Msec of effective exposure. In their paper, the authors provide catalogs of QSO properties, and describe their novel method of calculating X-ray flux upper limits and effective sky coverage. Spectroscopic redshifts are available for about 1/3 of the detected sample; elsewhere, redshifts are estimated photometrically. The authors have detected 56 QSOs with redshift z > 3, substantially expanding the known sample. They find no evidence for evolution out to z ~ 5 for either the X-ray photon index Gamma or for the ratio of optical/UV to X-ray flux Alpha_ox. About 10% of detected QSOs show best-fit intrinsic absorbing columns greater than 1022 cm-2, but the fraction might reach ~1/3 if most nondetections are absorbed. The authors confirm a significant correlation between Alpha_ox and optical luminosity, but it flattens or disappears for fainter (M_B >~ -23) active galactic nucleus (AGN) alone. They report significant hardening of Gamma both toward higher X-ray luminosity, and for relatively X-ray loud quasars. These trends may represent a relative increase in nonthermal X-ray emission, and their findings thereby strengthen analogies between Galactic black hole binaries and AGN. For uniformly selected subsamples of narrow-line Seyfert 1s and narrow absorption line QSOs, they find no evidence for unusual distributions of either Alpha_ox or Gamma. Much more information on the SDSS is available at the project's web site at <a href="http://www.sdss.org/">http://www.sdss.org/</a>. This table was created by the HEASARC in April 2009 based on the machine-readable version of Table 2 ('Properties of SDSS Quasars Detected by Chandra') which was obtained from the ApJ website. This is a service provided by NASA HEASARC .

ROSAT All-Sky Survey Bright Source Catalog/Catalog of Principal Galaxies Matches

In a correlation study of the ROSAT All-Sky Survey Bright Source Catalog (RASS-BSC, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/XI/10">CDS Cat. <XI/10></a>, the HEASARC table RASSBSC) with the Catalogue of Principal Galaxies (PGC, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VII/119">CDS Cat. <VII/119></a>, the HEASARC table PGC2003), 904 X-ray sources were found that possess possible extragalactic counterparts within a search radius of 100 arcseconds. A visual screening process was applied to classify the reliability of the correlations. 547 correlations have been quoted as reliable identifications. From these, 349 sources are known to be active galaxies. Although for the other sources no hints for activity were found in the literature, 69% of those for which we have distances show X-ray luminosities exceeding those of normal galaxies, a clear sign that these galaxies also own hitherto unreported X-ray active components. Some objects are located inside or in the direction of a known group or cluster of galaxies. Their X-ray flux may therefore be in part affected by hot gas emission. In the paper, luminosity and log N-log S distributions are used to characterize different subsamples. Nuclei that are both optically and X-ray active are found predominantly in spirals. Two special source samples are defined, one with candidates for X-ray emission from hitherto unknown groups or clusters of galaxies, and one with high X-ray luminosity sources, that are likely candidates to possess hitherto unreported active galactic nuclei. Besides a compilation of X-ray and optical parameters, X-ray overlays on optical images for all the objects are also supplied as part of this work. This table contains 1124 optical galaxy entries for the 904 relevant X-ray candidates/counterparts from the RASS. Besides a compilation of X-ray and optical parameters for each source, the results of an identification screening are also given. The 904 optical images with X-ray overlay contours (xID_nnn.ps.gz) used in the screening process are added for each user's own judgement of the reliability of the associations. This table was created by the HEASARC in March 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/378/30">CDS catalog J/A+A/378/30</a> file table1.dat, the list of PGC galaxies identified as possible counterparts to RASS Bright Source Catalog X-ray sources. This is a service provided by NASA HEASARC .

ROSAT All-Sky Survey Candidate Isolated Neutron Stars

Using new and archival observations made with the Swift satellite and other facilities, the authors examine 147 X-ray sources selected from the ROSAT All-Sky-Survey Bright Source Catalog (RASS/BSC) to produce a new limit on the number of isolated neutron stars (INSs) in the RASS/BSC, the most constraining such limit to date. Independent of X-ray spectrum and variability, the number of INSs is <= 48 (90% confidence). Restricting attention to soft (kTeff < 200 eV), non-variable X-ray sources - as in a previous study - yields an all-sky limit of <= 31 INSs. In the course of their analysis, the authors identify 5 new high-quality INS candidates for targeted follow-up observations. A future all-sky X-ray survey with eROSITA, or another mission with similar capabilities, can be expected to increase the detected population of X-ray-discovered INSs from the 8 - 50 in the BSC, to (for a disk population) 240 - 1500, which will enable a more detailed study of neutron star population models. Following selection of the INS candidates, short (~ 1 ks) follow-up observations with Swift/XRT were obtained for 92 of the candidates; these observations decreased the X-ray positional uncertainty (the systematic positional error associated with Swift blind pointing observations is on the order of 3.5"). The authors obtained (where possible) contemporaneous UV observations with Swift/UVOT for counterpart identification with off-band objects. This table was created by the HEASARC in May 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/714/1424">CDS Catalog J/ApJ/714/1424</a> files table1.dat and table2.dat. This is a service provided by NASA HEASARC .

Swift-BAT 157-Month All-Sky Hard X-Ray Survey

This catalog includes the hard X-ray sources detected in the first 157 months of observations with the Burst Alert Telescope (BAT) coded-mask imager on board the Swift observatory. The results of the 157 months survey catalog has been obtained using data from February 2007 to December 2017 and provide a uniform hard X-ray all-sky survey with a sensitivity of 8.40 x 10-12 erg/s/cm2 over 90% of the sky and 7.24 x 10-12 erg/s/cm2 over 50% of the sky in the 14-195 keV band. The exposure time in all sky ranges from ~ 15 Ms to ~ 35 Ms, where ~ 50% of the sky achieves an exposure time of ~ 22.8 Ms. The 157 months survey provides 1891 hard X-ray sources in the 14-195 keV band above the 4.8 sigma significance level, where 259 are new detections from the 105-month catalog of which 54 are previously known source in X-ray. The sources identification is mostly from NED and SIMBAD and the 157-month catalog reports for positive identification the counterpart R.A. and Dec and the alternative name. The sources are classified in 17 different classes as follows: <pre> Class Source Type Number of Sources 0 Unknown 221 1 Galactic 4 2 Galaxy 16 3 Galaxy Cluster 26 4 Seyfert I 446 5 Seyfert II 464 6 Other AGN 130 7 Beamed AGN (Blazar/FSRQ) 192 8 LINER 7 9 Cataclysmic Variable Star (CV) 81 10 Pulsar 27 11 Supernova Remnant (SNR) 7 12 Star 26 13 High Mass X-ray Binary (HMXB) 108 14 Low Mass X-ray Binary (LMXB) 118 15 Other X-ray Binary (XRB) 17 16 Tidal Disruption Event 1 Total 1891 </pre> The data reduction, analysis, and catalog generation of the Swift-BAT are conducted following the same procedures of the previous catalog survey (Tueller+ 2010, J/ApJS/1167/186, Baumgartner+ 2013, J/ApJS/207/19). The BAT survey data are collected into arrays (Detector Plane Histograms, DPHs) where the data are binned in ~ 300 s time interval and in 8 energy band channels (14-20, 20-24, 24-35, 35-50, 50-75, 75-100, 100- 197 150, and 150-195 keV) and 1 energy total band (14-195 keV). Three different mosaic images are created from the DPH dividing the sky in 6 regions. The first set has images created in 8 energy bands to span a contiguous time interval (snapshot). The second set has images co-adding data on a time period of a month. The third set is created in 8 energy bands by Crab-weighting the monthly images in each of the energy band with the following weights (Baumgartner+ 2013, J/ApJS/207/19): 27.000, 35.260, 22.700, 29.444, 21.272, 16.062, 8.449, 2.630. The benchmark Crab spectrum adopted is F(E) = 10.17Eâ2.15 photon cm2 s keV. The source detection algorithm uses the Crab-weighted mosaic images. For each source detected lightcurves and spectra are derived. The lightcurves are obtained from the snapshot images, the mosaic monthly images and the Crab-weighted mosaic images. The spectra are obtained from an additional set of mosaic images by adding all the snapshots for the 157 months period in 8-bands. All the analyses use HEASoft tools version 6.23, and the most recent BAT calibration database (updated on Oct. 3, 2017). Data products are generated for each source detected and these are: three different lightcurves in FITS format obtained from the snapshot, monthly and Crab-weighted monthly mosaic images and the equivalent plots as GIF images; an 8-channel average spectrum in FITS obtained using all 157 months; and a GIF file showing the spectrum with the fit to the best parameter of the power-law model. The snapshot lightcurves report rates for the 8-energy band, the monthly and Crab-weighted monthly mosaic lightcurves reports rated for the 8-energy band and the total band 14-195 keV. This table was ingested by the HEASARC in February 2025 based upon the published 157-month catalog. The catalog is also available at <a href="https://swift.gsfc.nasa.gov/results/bs157mon/">https://swift.gsfc.nasa.gov/results/bs157mon/</a>. This is a service provided by NASA HEASARC .

AAVSO Photometric All Sky Survey ConeSearch

All MAST catalog holdings are available via Cone Search endpoints. This service provides access to the MAST mirror of the AAVSO Photometric All Sky SurveyAll available missions are listed at http://archive.stsci.edu/vo/mast_services.html.

Sloan Digital Sky Survey NBC Quasar Candidate Catalog

The Nonparametric Bayes Classifier (NBC) Quasar Candidate Catalog is a catalog of 100,563 unresolved, UV-excess (UVX) quasar candidates with magnitudes to as faint as 21 in the g-band from 2099 square degrees of the Sloan Digital Sky Survey (SDSS) Data Release One (DR1) imaging data. Existing spectra of 22,737 sources reveals that 22,191 (97.6%) are quasars; accounting for the magnitude dependence of this efficiency, the authors estimate that 95,502 (95.0%) of the objects in the catalog are quasars. Such a high efficiency is unprecedented in broadband surveys of quasars. This "proof-of-concept" sample is designed to be maximally efficient, but still has 94.7% completeness to unresolved, g ~< 19.5, UVX quasars from the DR1 quasar catalog. This efficient and complete selection is the result of the application of a probability density type analysis to training sets that describe the four-dimensional color distribution of stars and spectroscopically confirmed quasars in the SDSS. Specifically, the authors use a nonparametric Bayesian classification, based on kernel density estimation, to parametrize the color distribution of astronomical sources - allowing for fast and robust classification. They further supplement the catalog by providing photometric redshifts and matches to FIRST/VLA, ROSAT, and USNO-B sources. Much more information on the SDSS is available at the project's web site at <a href="http://www.sdss.org/">http://www.sdss.org/</a>. This database table was created by the HEASARC in August 2005 based on CDS table J/ApJS/155/257/table1.dat. This is a service provided by NASA HEASARC .

AKARI/IRC All-Sky Survey Point Source Catalog, Version 1

The AKARI Infrared Astronomical Satellite observed the whole sky in the far-infrared (50-180 microns or um) and the mid-infrared (9 and 18 um) between May 2006 and August 2007 (Murakami et al. 2007PASJ...59S.369M) in six infrared bands between 9 um and 180 um. The AKARI/IRC Point Source Catalogue, Version 1.0 provides positions and fluxes for 870,973 sources observed with the InfraRed Camera (IRC): 844,649 sources in the S9W filter, and 194,551 sources in the L18W filter; the table below provides a summary of the IRC filter characteristics: <pre> Filter: S9W L18W Center(µm): 9 18 Width(µm): 4.10 9.97 Range(µm): 6.7-11.6 13.9-25.6 Pixel("): 9.4x9.4 10.4x9.4 Limit(mJy): 50 120 [at 5{sigma}] </pre> The users of the catalog are requested to carefully read the release note at <a href="http://www.ir.isas.jaxa.jp/AKARI/Observation/">http://www.ir.isas.jaxa.jp/AKARI/Observation/</a> before critical discussions of the data. Any questions and comments are appreciated at ISAS Helpdesk (iris_help@ir.isas.jaxa.jp) Please acknowledge the usage of the AKARI data (details at <a href="http://www.ir.isas.jaxa.jp/AKARI/Publications/guideline.html">http://www.ir.isas.jaxa.jp/AKARI/Publications/guideline.html</a>). This table was created by the HEASARC in May 2010 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/II/297">CDS catalog II/297</a> file irc.dat. This is a service provided by NASA HEASARC .

Sloan Digital Sky Survey (DR5)/XMM-Newton Quasar Survey Catalog

This table contains the 5th Data Release Sloan Digital Sky Survey (DR5 SDSS)/XMM-Newton Quasar Survey Catalog. This catalog contains 792 SDSS DR5 quasars with optical spectra that have been observed serendipitously in the X-rays with XMM-Newton. These quasars cover a redshift range of z = 0.11 - 5.41 and a magnitude range of i = 15.3 - 20.7. Substantial numbers of radio-loud (70) and broad absorption line (51) quasars exist within this sample. Significant X-ray detections at >=2 sigma account for 87% of the sample (685 quasars), and 473 quasars are detected at >=6 sigma, sufficient to allow X-ray spectral fits. For detected sources, ~60% have X-ray fluxes between F(2-10 keV) = (1-10) x 10-14 erg cm-2 s-1. The authors fit a single power law, a fixed power law with intrinsic absorption left free to vary, and an absorbed power-law model to all quasars with X-ray signal-to-noise ratio >= 6, resulting in a weighted mean photon index Gamma = 1.91 +/- 0.08, with an intrinsic dispersion sigma(Gamma) = 0.38. For the 55 sources (11.6%) that prefer intrinsic absorption, the authors find a weighted mean NH = 1.5 +/- 0.3 x 1021 cm-2. They find that Gamma correlates significantly with optical color, Delta(g-i), the optical-to-X-ray spectral index (alphaox), and the X-ray luminosity. While the first two correlations can be explained as artifacts of undetected intrinsic absorption, the correlation between Gamma and X-ray luminosity appears to be a real physical correlation, indicating a pivot in the X-ray slope. This table was created by the HEASARC in July 2009 based on electronic versions of Tables 1 and 2 from the paper which were obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .

Sloan Digital Sky Survey Unusual Quasars Catalog

Large spectroscopic surveys have discovered very peculiar and hitherto unknown types of active galactic nuclei (AGN). Such rare objects may hold clues to the accretion history of the supermassive black holes at the centres of galaxies. The authors aim to create a sizeable sample of unusual quasars from the unprecedented spectroscopic database of the Sloan Digital Sky Survey (SDSS). This table contains a catalog of 1005 quasars with unusual spectra in the redshift interval from 0.6 to 4.3. [HEASARC Note: the redshifts in this table actually range from 0.497 to 4.771]. The quasars were selected from the Sloan Digital Sky Survey Data Release 7 (Abazajian et al., 2009, ApJS, 182, 543) by means of Kohonen self-organising maps. The spectra are dominated by either broad absorption lines (42%), unusual red continua (27%), weak emission lines (18%), or conspicuously strong optical and/or UV iron emission (11%). This large sample provides a useful resource for both studying properties and relations of/between different types of unusual quasars and selecting particularly interesting objects, even though the compilation is not aimed at completeness in a quantifiable sense. The spectra are grouped into seven types. The catalogue contains the redshift, the absolute magnitude, the spectral type, the radio loudness parameter, a peculiarity index, and some comments on peculiar spectral features. This table was created by the HEASARC in May 2012 based on CDS table J/A+A/541/A77 file table3.dat. This is a service provided by NASA HEASARC .