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- ID:
- ivo://nasa.heasarc/galexlog
- Title:
- Galaxy Evolution Explorer (GALEX) Observation Log
- Short Name:
- GALEXLOG
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Galaxy Evolution Explorer (GALEX) observation log of the extant and planned observations to be made by this satellite observatory. The Galaxy Evolution Explorer (GALEX) is a NASA Small Explorer Mission launched on April 28, 2003. GALEX has been performing the first Space Ultraviolet sky survey. Five imaging surveys in each of two bands (FUV: 1350-1750 Angstroms and NUV: 1750-2800 Angstroms) range from an all-sky survey (limiting m<sub>AB</sub> ~ 20 - 21) to an ultra-deep survey of 4 square degrees (limiting m<sub>AB</sub> ~ 26). Three spectroscopic grism surveys (spectral resolution R = 100 - 300) are underway with various depths (m<sub>AB</sub> ~ 20 - 25) and sky coverage (100 to 2 square degrees) over the 1350 - 2800 Angstroms spectral range. The instrument includes a 50-cm modified Ritchey-Chretien telescope, a dichroic beam splitter and astigmatism corrector, two large, sealed-tube microchannel plate detectors to simultaneously cover the two bands and the 1.2-degree field of view. A rotating wheel provides either imaging or grism spectroscopy with transmitting optics. The GALEX mission also includes an Associate Investigator program for additional observations and supporting data analysis which supports a wide variety of investigations made possible by the first UV sky survey. The HEASARC provides this table of GALEX observations as an assistance to the high-energy astrophysics community, e.g., to enable cross-correlations of GALEX with X-ray observations. The GALEX data are available via MAST at <a href="http://galex.stsci.edu/">http://galex.stsci.edu/</a>. More information about GALEX can be found at <a href="http://www.galex.caltech.edu/">http://www.galex.caltech.edu/</a> and <a href="https://asd.gsfc.nasa.gov/archive/galex/">https://asd.gsfc.nasa.gov/archive/galex/</a>. This table was first created in July 2010 using the input file <a href="http://sherpa.caltech.edu/gips/ref/galex_obs_status.csv">http://sherpa.caltech.edu/gips/ref/galex_obs_status.csv</a> obtained from the Caltech GALEX site. This table is updated within a week of the update of the original file. This is a service provided by NASA HEASARC .
- ID:
- ivo://archive.stsci.edu/catalogs/GALEX
- Title:
- GALEX ConeSearch
- Short Name:
- GALEX CS
- Date:
- 23 Jul 2020 20:30:39
- Publisher:
- Space Telescope Science Institute Archive
- Description:
- All MAST catalog holdings are available via a ConeSearch endpoint. GALEX data are available via the standard MAST CS service,and an auxiliary service for GALEX data only. This catalog includes Galex GR 6/7 data, thus including the closeout release, as described at https://galex.stsci.edu/GR6/. The Galaxy Evolution Explorer (GALEX), a NASA Small Explorer mission, performed the first all-sky, deep imaging and spectroscopic ultraviolet surveys in space. The prime goal of GALEX was to study star formation in galaxies and its evolution with time. All available missions are listed at http://archive.stsci.edu/vo/mast_services.html.
- ID:
- ivo://CDS.VizieR/II/312
- Title:
- GALEX-DR5 (GR5) sources from AIS and MIS
- Short Name:
- II/312
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galaxy Evolution Explorer (GALEX) is an ultraviolet space telescope launched in 2003. It observes in 2 ultraviolet bands, FUV (far-UV) and NEV (near-UV), which characteristics are: -------------------------------------------------------------------- FUV NUV -------------------------------------------------------------------- Bandwidth 1344-1786 1771-2831 ({AA}) Effective wavelength 1538.6 2315.7 ({AA}) Astrometry (R<0.6deg) 0.59 0.49 (arcsec) Photometry 0.05 0.03 (ABmag) Zero point 18.82 20.08 (ABmag) Image resolution 4.2 5.3 (arcsec/pix) Spectral resolution 200 118 ({delta}{lambda}/{lambda}) -------------------------------------------------------------------- Two catalogs of UV sources from GALEX surveys are provided: * the All-sky Imaging Survey (AIS), containing 65.3million sources over 21435 square degrees, has a 5{sigma} depth in FUV/NUV of 19.9/20.8 (AB magnitudes); * the Medium-depth Imaging Survey (MIS), with 12.6million sources, covers 1579 square degrees and has a 5{sigma} depth in FUV/NUV of 22.6/22.7 (AB magnitudes). See also the description by Bianchi et al. (2011MNRAS.411.2770B)
- ID:
- ivo://nasa.heasarc/galextdsc
- Title:
- GALEX Time Domain Survey Catalog
- Short Name:
- GALEXTDSC
- Date:
- 18 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 .
- ID:
- ivo://CDS.VizieR/J/ApJ/724/1389
- Title:
- Mapping the diffuse UV sky with GALEX
- Short Name:
- J/ApJ/724/1389
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a map of the diffuse ultraviolet cosmic background in two wavelength bands (FUV: 1530{AA} and NUV: 2310{AA}) over almost 75% of the sky using archival data from the Galaxy Evolution Explorer (GALEX) mission. Most of the diffuse flux is due to dust-scattered starlight and follows a cosecant law with slopes of 545 photons/cm^2^/s/sr/{AA} and 433 photons/cm^2^/s/sr/{AA} in the FUV and NUV bands, respectively. There is a strong correlation with the 100um Infrared Astronomy Satellite (IRAS) flux with an average UV/IR ratio of 300 photons/cm^2^/s/sr/{AA}/(MJy/sr) in the FUV band and that of 220 photons/cm^2^/s/sr/{AA}/(MJy/sr) in the NUV band but with significant variations over the sky. In addition to the large-scale distribution of the diffuse light, we note a number of individual features including bright spots around the hot stars Spica and Achernar.
- ID:
- ivo://nasa.heasarc/nuvbemdcat
- Title:
- Near-UV Detected Bright Early-M Dwarf Star Catalog
- Short Name:
- NUVBEMDCAT
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Planets orbiting within the close-in habitable zones of M dwarf stars will be exposed to elevated high-energy radiation driven by strong magnetohydrodynamic dynamos during stellar youth. Near-ultraviolet (NUV) irradiation can erode and alter the chemistry of planetary atmospheres, and a quantitative description of the evolution of NUV emission from M dwarfs is needed when modeling these effects. The authors investigated the NUV luminosity evolution of early M-type dwarfs by cross-correlating the Lepine & Gaidos (LG11: 2011, AJ, 142, 138) catalog of bright M dwarfs (available at the HEASARC as the MDWARFASC table) with the Galaxy Evolution Explorer (GALEX) catalog of NUV (1771-2831 Angstrom) sources. Of the 4,805 sources with GALEX counterparts, 797 have NUV emission significantly (> 2.5 sigma) in excess of an empirical basal level. The authors inspected these candidate active stars using visible-wavelength spectra, high-resolution adaptive optics imaging, time-series photometry, and literature searches to identify cases where the elevated NUV emission is due to unresolved background sources or stellar companions; they estimated the overall occurrence of these "false positives" (FPs) as ~ 16%. The authors constructed an NUV luminosity function that accounted for FPs, detection biases of the source catalogs, and GALEX upper limits. They found the NUV luminosity function to be inconsistent with predictions from a constant star-formation rate and simplified age-activity relation defined by a two-parameter power law. This table was created by the HEASARC in March 2015 based on an electronic versions of Table 4 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/II/335
- Title:
- Revised catalog of GALEX UV sources (GUVcat_AIS GR6+7)
- Short Name:
- II/335
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galaxy Evolution Explorer (GALEX) imaged the sky in two ultraviolet (UV) bands, far-UV (FUV, {lambda}_eff_~1528{AA}), and near-UV (NUV, {lambda}_eff_~2310{AA}), delivering the first comprehensive sky surveys at these wavelengths. The GALEX database contains FUV and NUV images, ~500 million source measurements and over 100000 low-resolution UV spectra. The UV surveys are a unique resource for statistical studies of hot stellar objects, z<~2 QSOs, star-forming galaxies, nebulae and the interstellar medium, and provide a roadmap for planning future UV instrumentation and follow-up observing programs. We present science-enhanced, "clean" catalogs of GALEX UV sources, with useful tags to facilitate scientific investigations. The catalogs are an improved and expanded version of our previous catalogs of UV sources (BCScat; Bianchi+, 2011, J/MNRAS/411/2770 ; II/312 and 2014AdSpR..53..900B). With respect to BCScat, we have patched 640 fields for which the pipeline had improperly coadded non-overlapping observations, and we provide a version with a larger sky coverage (about 10%) by relaxing the restriction to the central area of the GALEX field to 1.1{deg} diameter (GUVcat_AIS_fov055: GUVcat_AIS FOV_radius <0.55{deg}), as well as the cleaner, more restrictive version using only the 1{deg} central portion of each field as in BCScat (GUVcat_AIS_fov050: GUVcat_AIS FOV_radius <0.50{deg}). We added new tags to facilitate selection and cleaning of statistical samples for science applications: we flag sources within the footprint of extended objects (nearby galaxies, stellar clusters) so that these regions can be excluded for estimating source density. As in our previous catalogs, in GUVcat duplicate measurements of the same source are removed, so that each astrophysical object has only one entry. Such a unique-source catalog is needed to study the density and distributions of sources, and to match UV sources with catalogs at other wavelengths. The catalog includes all observations from the All-Sky Imaging Survey (AIS), the survey with the largest area coverage, with both FUV and NUV detectors exposed: over 28700 fields, made up of a total of 57000 observations ("visits"). The total area covered, when overlaps are removed and gaps are accounted for, is 24790 square degrees for GUVcat_AIS_fov055 (GUVcat_AIS_fov055) and 22125 square degrees for (GUVcat_AIS_fov050). The total numbers of "unique" AIS sources (eliminating duplicate measurements) are 82,992,086 (GUVcat_AIS_fov055) and 69,772,677 (GUVcat_AIS_fov050). The typical depth of the GUVcat_AIS catalog is FUV=19.9, NUV=20.8 AB mag.
