GLXSDSSQSO ivo://nasa.heasarc/glxsdssqso NASA/GSFC HEASARC Trammell et al. 2026-07-03 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Quasar This table contains the result of an analysis of the broad-band UV and optical properties of z ~< 3.4 quasars matched in the Galaxy Evolution Explorer (GALEX) General Data Release 1 (GR1) and the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3). Of the 6371 SDSS DR3 quasars covered by 204 GALEX GR1 tiles and listed in this table, 5380 (84%) have near-UV detections, while 3034 (48%) have both near-UV and far-UV detections using a matching radius of 7 arcseconds. Most of the DR3 sample quasars are detected in the near-UV until z ~ 1.7, with the near-UV detection fraction dropping to ~50% by z ~ 2. Statistical tests performed on the distributions of non-detections indicate that the optically selected quasars missed in the UV tend to be optically faint or at high redshift. The GALEX positions are shown to be consistent with the SDSS astrometry to within an rms scatter of 0.6 - 0.7 arcsecs in each coordinate, and the empirically determined photometric errors from multi-epoch GALEX observations significantly exceed the Poissonian errors quoted in the GR1 object catalogs. The UV-detected quasars are well separated from stars in UV-optical color-color space, with the UV-optical relative colors suggesting a marginally detected population of reddened objects due to absorption along the line of sight or dust associated with the quasar. The resulting spectral energy distributions (SEDs) cover ~350 - 9000 Angstroms (rest frame), where the overall median SED peaks near the Lyman-Alpha emission line, as found in other UV quasar studies. The large sample size allows the authors to construct median SEDs in small bins of redshift and luminosity, and they find that the median SED becomes harder (bluer) at UV wavelengths for quasars with lower continuum luminosity. The detected UV-optical flux as a function of redshift is qualitatively consistent with attenuation by intervening Lyman-absorbing clouds. This table was created by the HEASARC in October 2009 based on the electronic version of Table 2 from the reference paper which was obtained from the CDS (their catalog J/AJ/133/1780 file table2.dat). This is a service provided by NASA HEASARC . 2007AJ....133.1780T https://heasarc.gsfc.nasa.gov/W3Browse/all/glxsdssqso.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=glxsdssqso& GET text/xml 180 99999 true 8.642997 -11.215893 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=glxsdssqso GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_glxsdssqso&Action=More+Options&Action=Parameter+Search&ConeAdd=1 SDSS 0.0166666666666667 Optical UV public glxsdssqso GALEX/SDSS Quasar Catalog name SDSS DR3 Quasar Catalog Object Designation meta.id;meta.main char nullable galex_name GALEX GR1 Merged Object Catalog Designation meta.id.assoc char nullable ra SDSS Right Ascension degree pos.eq.ra;meta.main double nullable dec SDSS Declination degree pos.eq.dec;meta.main double nullable off_set GALEX/SDSS Coordinate Position Offset (arcsec) arcsec pos.angDistance;em.X-ray;em.UV double nullable redshift SDSS Derived Redshift src.redshift double nullable rmag SDSS PSF r Band Magnitude mag phot.mag;em.opt.R double nullable fmag GALEX GR1 f (FUV=120-177nm) Magnitude mag phot.mag;em.UV.100-200nm double nullable dec_galex GALEX Declination degree meta.id.assoc;pos.eq.dec double nullable fmag_error Error in GALEX GR1 f (FUV=120-177nm) Magnitude mag stat.error;phot.mag;em.UV.100-200nm double nullable abs_imag Absolute SDSS i Band Magnitude mag phys.magAbs;em.opt.I double nullable log_2200a_lum Logarithm of Monochromatic Luminosity at 2200 Angstroms log(erg/s) phys.luminosity;em.UV.200-300nm double nullable imag_error Error in SDSS PSF i Band Magnitude mag stat.error;phot.mag;em.opt.I double nullable gi_color Relative (g-i) Color Index mag phot.color;em.opt.B;em.opt.I double nullable fn_color Relative (f-n) Color index mag phot.color;em.UV.100-200nm;em.UV.200-300nm double nullable umag SDSS PSF u Band Magnitude mag phot.mag;em.opt.U double nullable fuv_exposure GALEX FUV Effective Exposure Time (s) s time.duration;obs.exposure;em.UV.100-200nm double nullable nuv_exposure GALEX NUV Effective Exposure Time (s) s time.duration;obs.exposure;em.UV.200-300nm double nullable nmag GALEX GR1 n (NUV=177-300nm) Magnitude mag phot.mag;em.UV.200-300nm double nullable gmag SDSS PSF g Band Magnitude mag phot.mag;em.opt.B double nullable nmag_alt_err Empirical Calibration Error in GALEX GR1 n (NUV=177-300nm) Magnitude mag stat.error;phot.mag;em.UV.200-300nm double nullable ra_galex GALEX Right Ascension degree meta.id.assoc;pos.eq.ra double nullable lii SDSS Galactic Longitude degree pos.galactic.lon double nullable nmag_error Error in GALEX GR1 n (NUV=177-300nm) Magnitude mag stat.error;phot.mag;em.UV.200-300nm double nullable gmag_error Error in SDSS PSF g Band Magnitude mag stat.error;phot.mag;em.opt.B double nullable galex_svy_flag GALEX Survey Identifier Flag meta.id;obs.field short nullable fmag_alt_err Empirical Calibration Error in GALEX GR1 f (FUV=120-177nm) Magnitude mag stat.error;phot.mag;em.UV.100-200nm double nullable zmag_error Error in SDSS PSF z Band Magnitude mag stat.error;phot.mag;em.opt.I double nullable bii SDSS Galactic Latitude degree pos.galactic.lat double nullable gal_abs_u Galactic Absorption in the SDSS u Band mag phys.absorption;em.opt.U double nullable rmag_error Error in SDSS PSF r Band Magnitude mag stat.error;phot.mag;em.opt.R double nullable imag SDSS PSF i Band Magnitude mag phot.mag;em.opt.I double nullable log_nh_gal Logarithm of Galactic HI Column Density log(cm^-2) phys.columnDensity double nullable off_axis Object Distance from GALEX Field Center (arcmin) arcmin instr.offset double nullable zmag SDSS PSF z Band Magnitude mag phot.mag;em.opt.I double nullable log_5100a_lum Logarithm of Monochromatic Luminosity at 5100 Angstroms log(erg/s) phys.luminosity;em.opt.V double nullable umag_error Error in SDSS PSF u Band Magnitude mag stat.error;phot.mag;em.opt.U double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable