- ID:
- ivo://nasa.heasarc/galextdsc
- Title:
- GALEX Time Domain Survey Catalog
- Short Name:
- GALEXTDSC
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in ~ 40 deg<sup>2</sup> of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of ~ 3 years. The GALEX TDS fields were designed to be in spatial and temporal coordination with the Pan-STARRS1 Medium Deep Survey, which provides deep optical imaging and simultaneous optical transient detections via image differencing. The authors characterize the GALEX photometric errors empirically as a function of mean magnitude, and select sources that vary at the 5-sigma level in at least one epoch. They measure the statistical properties of the UV variability, including the structure function on timescales of days and years, and report classifications for the GALEX TDS sample using a combination of optical host colors and morphology, UV light curve characteristics, and matches to archival X-ray, and spectroscopy catalogs. The authors classify 62% of the sources as active galaxies (358 quasars and 305 active galactic nuclei), and 10% as variable stars (including 37 RR Lyrae, 53 M dwarf flare stars, and 2 cataclysmic variables). They detect a large-amplitude tail in the UV variability distribution for M-dwarf flare stars and RR Lyrae, reaching up to |Delta-M| = 4.6 and 2.9 magnitudes, respectively. The mean amplitude of the structure function for quasars on year timescales is five times larger than observed at optical wavelengths. The remaining unclassified sources include UV-bright extragalactic transients, two of which have been spectroscopically confirmed to be a young core-collapse supernova and a flare from the tidal disruption of a star by a dormant super-massive black hole. The authors calculate a surface density for variable sources in the UV with NUV < 23 mag and |Delta-M| > 0.2 mag of ~ 8.0, 7.7, and 1.8 deg<sup>-2</sup> for quasars, AGN, and RR Lyrae stars, respectively, and a surface density rate in the UV for transient sources, using the effective survey time at the cadence appropriate to each class, of ~15 and 52 deg<sup>-2</sup> yr<sup>-1</sup> for M dwarfs and extragalactic transients, respectively. The GALEX observations were made using the NUV detector which has an 1.25 degree diameter field of view and an effective wavelength of 2316 Angstroms. During the window of observing visibility of each GALEX TDS field (from two to four weeks, one to two times per year), they were observed with a cadence of 2 days, and a typical exposure time per epoch of 1.5 ks (or a 5-sigma point-source limit of m<sub>AB</sub>(NUV) ~ 23.3 magnitude), with a range from 1.0 to 1.7 ks. Table 2 in the reference paper lists the RA and Dec of their centers, the Galactic extinction E(B - V ) for each field from the Schlegel et al. (1998, ApJ, 500, 525) dust maps, and the number of epochs per field. This table was created by the HEASARC in May 2013 based on a machine-readable version of Table 4 from the paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/mggammadet
- Title:
- Gamma-RaySourceDetailedCatalog(Macomb&Gehrels1999)
- Short Name:
- MGGAMMADET
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains the slightly revised contents of the detailed Tables 2A - 2G from the General Gamma-Ray Source Catalog of Macomb & Gehrels (1999). It lists details of all known gamma-ray observations within the energy range from 50 keV to ~1 TeV for 314 discrete gamma-ray sources that were listed in Tables 2A - 2G of the published version of this catalog, including all 310 sources listed in the published Summary Table 1, together with 4 sources (2CG 054+01, A0620-00, GX 340+0, and H1822-000) that were listed only in Table 2 of the published catalog but were (presumably accidentally) omitted from Table 1. The positions for the sources in the present database were taken from Table 1 of the General Gamma-Ray Source Catalog. Thus, this table is essentially a compilation of gamma-ray observations of discrete sources as known to the authors as of early 1999. There is another HEASARC database table called the Gamma-Ray Source Summary Catalog (Macomb & Gehrels 1999) or MGGAMMACAT that contains the summary information on these sources that was given in Table 1 of the General Gamma-Ray Source Catalog. As noted above, this is a slightly revised version compared to the published Tables 2A - 2G. The known differences between the HEASARC and published versions are discussed in the HEASARC_Version section of the help documentation. This database table was created by the HEASARC in March 2002 based upon machine-readable versions of Tables 2A-2G of the Macomb & Gehrels (1999) General Gamma-Ray Source Catalog that were supplied by the authors. One duplicate entry was removed from this table in June 2019. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/mggammacat
- Title:
- Gamma-RaySourceSummaryCatalog(Macomb&Gehrels1999&2001)
- Short Name:
- M&GGamma-ray
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table is a revised and updated version of the published General Gamma-Ray Source Catalog (Macomb & Gehrels 1999, ApJS, 120, 335). It contains all 309 gamma-ray point sources listed in Table 1 of the published version of this catalog; 4 gamma-ray point sources (2CG 054+01, A0620-00, GX 340+0, and H1822-000) added by the HEASARC that were listed in Table 2 of the published catalog but were (presumably accidentally) omitted from Table 1 of the published catalog; and 107 sources (106 sources from the 3rd Egret (3EG) catalog of Hartman et al. (1999, ApJS, 123, 79) and GEV J1732-3130) that were compiled by Macomb and Gehrels subsequent to their original publication (Macomb and Gehrels 2001, unpublished). Thus, the present database table is essentially a summary master list of all detected gamma-ray point sources as of circa 2000. There is another HEASARC database table called the Gamma-Ray Source Detailed Catalog (Macomb & Gehrels 1999 & 2001) or MGGAMMADET that contains detailed information on the gamma-ray properties of these sources such as fluxes and spectral indices and that is based on Tables 2A-2G of the Macomb & Gehrels paper. This database table was created by the HEASARC in March 2001 based on tables supplied to the HEASARC by the catalog authors which contained an updated version of Table 1 from the published paper. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gcvsegvars
- Title:
- General Catalog of Variable Stars (GCVS4.2): Extragalactic Variables
- Short Name:
- GCVS/X-gal
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The General Catalog of Variable Stars (GCVS) is the only reference source on all known variable stars. This database is based on the electronically-readable version as distributed by the Sternberg Astronomical Institute and Institute of Astronomy (Russian Acad. Sci.), Moscow. It is the catalog of extragalactic variable stars, an updated version of the list contained in the GCVS (4th edition), Volume V. The total number of entries in this database is 10979 variable stars in 35 stellar systems (including the Magellanic Clouds, the Andromeda Galaxy, etc.). These variables include 144 stars now considered to be non-members of the galaxies in whose fields they lie, and 92 more stars that are possible non-members. The present improved electronic version of the GCVS 4th Edition, Volumes I-V, combined with the Name-Lists of Variable Stars Nos. 67 - 77, is also available from the Sternberg Institute via anonymous ftp to <a href="ftp://ftp.sai.msu.su/pub/groups/cluster/gcvs/gcvs/">ftp://ftp.sai.msu.su/pub/groups/cluster/gcvs/gcvs/</a> and more information is available via the Web at <a href="http://www.sai.msu.su/groups/cluster/gcvs/gcvs/">http://www.sai.msu.su/groups/cluster/gcvs/gcvs/</a>. This online version of the GCVS Vol. V Catalog of Extragalactic Variable Stars was created by the HEASARC in January 2005 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/II/250">CDS Catalog II/250</a>, table evs_cat.dat. The latter was itself based on on an electronically-readable version that was distributed by the Sternberg Astronomical Institute and Institute of Astronomy (Russian Acad. Sci.), Moscow. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gcvs
- Title:
- General Catalog of Variable Stars (June 2022 Version)
- Short Name:
- GCVS
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Work aimed at compiling detailed catalogs of variable stars in the Galaxy, which has been carried out continuously by Moscow variable-star researchers since 1946 on behalf of the International Astronomical Union, has entered the stage of the publication of the 5th, completely electronic edition of the General Catalog of Variable Stars (GCVS). The GCVS 5.1 is freely accessible on the Internet. The authors recommend citing their paper as a unified reference to the 5th edition of the GCVS. The GCVS is the only reference source on all known variable stars. This version contains the electronically-readable version as distributed by the Sternberg Astronomical Institute and Institute of Astronomy (Russian Acad. Sci.), Moscow. After the publication of Volume III of the 4th edition of the GCVS, the subsequent Name-lists with numbers from 67 to 77 contained only names of variable stars in the GCVS systems, together with their coordinates and variability types. The authors actually started compiling the 5th edition of the GCVS ten years ago, with the 78th Name-list of Variable Stars, which provided (as did all subsequent Name-lists) complete GCVS information for each star (in addition to the variability types, ranges of brightness variations, epochs of brightness maxima or minima, periods, etc.). In all, the 78th-81st Name-lists contain more than 13300 variable stars. The complete revision of information on the coordinates of variable stars (see the Introduction section of the reference paper) was also a part of the transition to the 5th edition. The present electronic version of the GCVS5.1 is available from Sternberg Astronomical Institute (Lomonosov Moscow University) and Institute of Astronomy (Russian Academy of Sciences) at <a href="http://www.sai.msu.su/gcvs/gcvs/">http://www.sai.msu.su/gcvs/gcvs/</a> as a first release of the fifth GCVS edition. Information on the contents and principles of the fifth edition can be found in Samus et al. (2017), the official reference to GCVS 5.1. The GCVS 5.1 version contains data for individual variable objects discovered and named as variable stars by 2021 and located mainly in the Milky Way galaxy. The total number of named variable stars, not counting designated non-existing stars or stars subsequently identified with earlier-named variables, is now 58035. The stars of the GCVS 5.1 are stars of the GCVS fourth edition plus Name-lists Nos. 67-84. The stars from the Name-lists Nos.78-84 are presented in the complete GCVS format. Complete information for stars of the Name-lists Nos. 67-77 is so far provided in the first 20 constellations (Andromeda to Cepheus). In these constellations, the GCVS information has been completely revised with active use of new publications as well as observations retrieved by the GCVS compilers by data mining and used to determine new variability types and new light elements whenever possible. The authors are continuing this work and will introduce new data for the next constellations as soon as they are ready. This version of the GCVS catalog was last updated by the HEASARC in September 2022, based on the file at <a href="http://www.sai.msu.su/gcvs/gcvs/gcvs5/gcvs5.txt">http://www.sai.msu.su/gcvs/gcvs/gcvs5/gcvs5.txt</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gcvsnsvars
- Title:
- General Catalog of Variable Stars, March 2012 Version: Suspected Variable Stars
- Short Name:
- GCVS/?
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This catalog is a compilation of stars that have been suspected of variability but have (mostly) not been finally designated as variables. It is the merging and latest updated version of the compilation of the New Catalog of Suspected Variable Stars (NSV Catalog) originally published in 1982 by Kukarkin et al. and the Supplement to the NSV originally published in 1998 by Kazarovets et al. This version (NSV Release 2) has updated the previous catalog in several ways. The accuracy of coordinates has been drastically improved for the objects in the catalog; for most of them, the authors have revised the photometric and spectroscopic data and updated the remarks. In the cases with no existing finding charts, the authors recovered variability of 2800 stars of the catalog, despite large errors of the previously published coordinates. The data contained in the present catalog include positions, magnitudes, variability types, references to the literature, and spectra. This version of the GCVS catalog was last updated by the HEASARC in September 2022, based on the files <a href="http://www.sai.msu.su/gcvs/gcvs/nsv2/nsv2.txt">http://www.sai.msu.su/gcvs/gcvs/nsv2/nsv2.txt</a> and <a href="http://www.sai.msu.su/gcvs/gcvs/nsvsup/nsvs.dat">http://www.sai.msu.su/gcvs/gcvs/nsvsup/nsvs.dat</a>. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtas150m
- Title:
- Giant Metrewave Radio Telescope All-Sky 150-MHz Radio Source Catalog
- Short Name:
- GMRTAS150M
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains results from the first full release of a survey of the 150-MHz radio sky, observed with the Giant Metrewave Radio Telescope (GMRT) between April 2010 and March 2012 as part of the TIFR GMRT Sky Survey (TGSS) project. Aimed at producing a reliable compact source survey, the authors' automated data-reduction pipeline efficiently processed more than 2000 hours of observations with minimal human interaction. Through application of innovative techniques such as image-based flagging, direction-dependent calibration of ionospheric phase errors, correcting for systematic offsets in antenna pointing, and improving the primary beam model, the authors created good quality images for over 95% of the 5,336 pointings. This data release covers 36,900 deg<sup>2</sup> (or 3.6 pi steradians) of the sky between -53 and +90 degrees Declination, which is 90% of the total sky. The majority of pointing images has a noise level below 5 mJy/beam (the median RMS background noise is 3.5 mJy per beam), with an approximate resolution of 25" x 25" (or 25" x 25"/cos(Dec-19<sup>o</sup>) for pointings south of 19 degrees Declination). The authors have produced a catalog of 0.62 Million radio sources with flux densities ranging from 11.1 mJy to 9.22 kJy that are derived from an initial, high-reliability source extraction at the 7-sigma level. For the bulk of the survey, the measured overall astrometric accuracy is better than 2 arcseconds in Right Ascension and Declination, while the flux density accuracy is estimated at approximately 10%. Within the scope of the TGSS Alternative Data Release (TGSS ADR) project, the source catalog, as well as 5,336 mosaic images (5 x 5 degree<sup>2</sup>) and an image cutout service, are made publicly available as a service to the astronomical community. (The TGSS images and cutout server are available through the project website at <a href="http://tgssadr.strw.leidenuniv.nl/">http://tgssadr.strw.leidenuniv.nl/</a>). In addition to enabling a wide range of different scientific investigations, the authors anticipate that these survey products will provide a solid reference for various new low-frequency radio aperture array telescopes (LOFAR, LWA, MWA, SKA-low), and can play an important role in characterizing the epoch-of-reionization (EoR) foreground. The TGSS ADR project aims at continuously improving the quality of the survey data products. Near-future improvements include replacement of bright source snapshot images with archival targeted observations, using new observations to fill the holes in sky coverage and to replace very poor quality observational data, and an improved flux calibration strategy for less severely affected observational data. This table was created by the HEASARC in February 2017 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/598/A78">CDS Catalog J/A+A/598/A78</a> file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtelain2
- Title:
- Giant Metrewave Radio Telescope ELAIS-N2 Field 610-MHz Radio Source Catalog
- Short Name:
- GMRTELAIN2
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a source catalog based on observations of the European Large-Area ISO Survey-North 2 (ELAIS-N2) field taken at 610 MHz with the Giant Metrewave Radio Telescope (GMRT). Thirteen pointings were observed, covering a total area of ~ 6 square degrees with a resolution of 6.5 x 5 arcsec<sup>2</sup>, position angle of +70 degrees. The rms noise at the center of the pointings is typically ~ 85 microJansky (µJy) before correction for the GMRT primary beam . The techniques used for data reduction and production of a mosaicked image of the region are described in the reference paper, where the final mosaic, along with a catalog of 1310 sources detected above a 6-sigma threshold, are presented. The survey complements existing radio and infrared data that are available for this region. For further details of the surveys and data analysis procedures, please refer to the published paper. This table contains the ELAIS-N2 catalog of 1310 detected 610-MHz radio sources. This table was created by the HEASARC in February 2012 based the source catalog of the Cambridge GMRT Survey of the ELAIS-N2 region which was obtained from the University of Cambridge Astrophysics Group Surveys and Catalogs website at <a href="http://www.mrao.cam.ac.uk/facilities/surveys/gmrt/elais-n2/">http://www.mrao.cam.ac.uk/facilities/surveys/gmrt/elais-n2/</a> file GMRT_EN2_dr1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrtelain1
- Title:
- Giant Metrewave Radio Telescope ELAIS-N1 Field 610-MHz Radio Source Catalog
- Short Name:
- GMRTELAIN1
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a source catalog based on observations of the European Large-Area ISO Survey-North 1 (ELAIS-N1) field taken at 610 MHz with the Giant Metrewave Radio Telescope. Nineteen pointings were observed, covering a total area of ~ 9 square degrees with a resolution of 6 x 5 arcsec<sup>2</sup>, position angle of +45 degrees. Four of the pointings were deep observations with an rms of ~ 40 microJansky (µJy) before primary beam correction, with the remaining fifteen pointings having an rms of ~ 70 uJy. The techniques used for data reduction and production of a mosaicked image of the region are described in the reference paper, where the final mosaic, along with a catalog of 2500 sources detected above a 6-sigma threshold, are presented. This work complements the large amount of optical and infrared data already available on the region. In their paper, the authors calculate 610-MHz source counts down to 270 uJy, and find further evidence for the turnover in differential number counts below 1 mJy, previously seen at both 610 MHz and 1.4 GHz. For further details of the surveys and data analysis procedures, please refer to the published paper. This table contains the ELAIS-N1 catalog of 2500 detected 610-MHz radio sources. This table was created by the HEASARC in February 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/383/75">CDS Catalog J/MNRAS/383/75</a> file catalog.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/gmrt4f150m
- Title:
- Giant Metrewave Radio Telescope Field I 150-MHz Radio Source Catalog
- Short Name:
- GMRT4F150M
- Date:
- 25 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Foreground removal is a major challenge for detecting the redshifted 21-cm neutral hydrogen (HI) signal from the Epoch of Reionization. The authors have used 150-MHz Giant Metrewave Radio Telescope (GMRT) observations to characterize the statistical properties of the foregrounds in four different fields of view. The observational data were used to assess point source subtraction. Considering the brightest source (~1 Jy) in each field, the authors find that the residual artefacts are less than 1.5% in the most sensitive field (FIELD I). Considering all the sources in the fields, they find that the bulk of the image is free of artefacts, the artefacts being localized to the vicinity of the brightest sources. The authors have used FIELD I, which has an rms noise of 1.3 mJy beam<sup>-1</sup>, to study the properties of the radio source population to a limiting flux of 9 mJy. The differential source count is well fitted with a single power law of slope -1.6. They find there is no evidence for flattening of the source counts towards lower flux densities which suggests that source population is dominated by the classical radio-loud active galactic nuclei. The authors have observed FIELD I in GMRT Time Allocation Committee (GTAC) cycle 15 in 2008 January, whereas FIELD II and FIELD III were observed in cycle 17 during 2010 February. These target fields were selected at high Galactic latitudes (b > 10<sup>o</sup>) which were up at night time during the GTAC cycles 15 and 17, and which contain relatively few bright sources (>= 0.3 Jy) in the 1400 MHz NRAO VLA Sky Survey (NVSS). Finally, FIELD IV was observed in cycle 8 (2005 June). Full details of these 4 observations are given in Table 1 of the reference paper. This table contains the 150-MHz source catalog for the most sensitive observation, namely the 9.8-hour observation of Field I (centered on J2000.0 RA and Dec of 5<sup>h</sup> 30<sup>m</sup> 00<sup>s</sup>, +60<sup>o</sup> 00' 00"), which was made on 2008 January 8. This table was created by the HEASARC in September 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/426/3295">CDS Catalog J/MNRAS/426/3295</a> file tablea1.dat This is a service provided by NASA HEASARC .
