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SDSSQUASAR - Sloan Digital Sky Survey Quasar Catalog (7th Data Release)

HEASARC
Archive

Overview

This table contains the fifth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog, which is based upon the SDSS Seventh Data Release. The catalog, which contains 105,783 spectroscopically confirmed quasars, represents the conclusion of the SDSS-I and SDSS-II quasar survey. There is an increase of 28,354 entries over the previous edition. The catalog consists of the SDSS objects that have luminosities larger than an absolute i-magnitude M_i = -22.0 (in a cosmology with H_0 = 70 km s-1 Mpc-1, Omega_M = 0.3, and Omega_Lambda = 0.7), have at least one emission line with a FWHM larger than 1000 km s-1 or have interesting/complex absorption features, are fainter than an apparent i magnitude ~ 15.0, and have highly reliable redshifts. The area covered by the catalog is ~ 9380 deg2. The quasar redshifts range from 0.065 to 5.46, with a median value of 1.49; the catalog includes 1248 quasars at redshifts greater than 4, of which 56 are at redshifts greater than 5. The catalog contains 9210 quasars with i < 18; slightly over half of the entries have i < 19. For each object the catalog presents positions accurate to better than 0.1" rms per coordinate, five-band (ugriz) CCD-based photometry with typical accuracy of 0.03 magnitudes, and information on the morphology and selection method. The catalog also contains basic radio, near-infrared, and X-ray emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra cover the wavelength region 3800-9200 Angstroms at a spectral resolution of ~ 2000; the spectra can be retrieved from the SDSS public database using the information provided in the catalog. Over 96% of the objects in the catalog were discovered by the SDSS.

Much more information on the SDSS is available at the project's web site at http://www.sdss.org/.


Catalog Bibcode

2010AJ....139.2360S

References

The Sloan Digital Sky Survey Quasar Catalog V (7th Data Release)
    Schneider D.P., Richards G.T., Hall P.B., Strauss M.A.,
    Anderson S.F., Boroson T.A., Ross N.P., Shen Y., Brandt W.N., Fan X.,
    Inada N., Jester S., Knapp G.R., Krawczyk C.M., Thakar A.R.,
    Vanden Berk D.E., Voges W., Yanny B., York D.G., Bahcall N.A., Bizyaev D.,
    Blanton M.R., Brewington H., Brinkmann J., Eisenstein D., Frieman J.A.,
    Fukugita M., Gray J., Gunn J.E., Hibon P., Ivezic Z., Kent S.M., Kron R.G.,
    Lee M.G., Lupton R.H., Malanushenko E., Malanushenko V., Oravetz D.,
    Pan K., Pier J.R., Price T.N. III, Saxe D.H., Schlegel D.J., Simmons A.,
    Snedden S.A., SubbaRao M.U., Szalay A.S., Weinberg D.H.
   <Astron. J., 139, 2360-2373 (2010)>
   =2010AJ....139.2360S


Provenance

This table was created by the HEASARC in June 2010 based on the electronic version of Table 2 from the above paper obtained from the AJ web site.

HEASARC Implementation

The HEASARC added a parameter (herein called flux_20_cm) which gives the FIRST flux density in mJy, which is calculated from the mag_20_cm parameter given in the published catalog. The RASS count rate CR, which was given as the logarithm of the count rate in the published catalog, is given herein as the actual count rate CR rather than the log of CR.

Parameters

Name
The J2000 position-based DR7 object designation, given in the format 'SDSS Jhhmmss.ss+ddmmss.s'. The coordinates in the object name follow the IAU convention and are truncated, not rounded.

RA
The Right Ascension of the quasar in the selected equinox. This was given in J2000 decimal degrees to a precision of 10-6 degrees in the original table. The positions for the objects are accurate to 0.1" rms or better in each coordinate. The SDSS coordinates are placed in the International Celestial Reference System (ICRS), primarily through the US Naval Observatory CCD Astrograph Catalog (Zacharias et al. 2000, AJ, 120, 2131).

Dec
The Declination of the quasar in the selected equinox. This was given in J2000 decimal degrees to a precision of 10-6 degrees in the original table. The positions for the objects are accurate to 0.1" rms or better in each coordinate. The SDSS coordinates are placed in the International Celestial Reference System (ICRS), primarily through the US Naval Observatory CCD Astrograph Catalog (Zacharias et al. 2000, AJ, 120, 2131).

LII
The Galactic Longitude of the quasar.

BII
The Galactic Latitude of the quasar.

Redshift
The quasar redshift. Given the considerable size of the DR7 quasar candidate list, the authors' previous practice of visually examining every spectrum, irrespective of whether it had been reviewed for a previous edition of the catalog, was abandoned. Only those objects whose DR7 spectra (identified by the Modified Julian Date of observation, plate number, and fiber number) were not in the Schneider et al. (2007, AJ, 134, 102: Paper IV) list were by default reviewed (55,666 spectra). The authors also visually examined the spectra for the 1224 quasars whose Paper IV redshifts differed by the DR7 spectro1d values by more than 0.03.

The SDSS spectra of these quasar candidates were manually inspected by several of the authors; as in previous papers in this series, they found that the spectroscopic pipeline redshifts and classifications of the overwhelming majority of the objects were accurate. The redshifts for 2671 of the quasar candidates were manually adjusted, usually by significant (several tenths or more) amounts; the main cause for revision, as one would expect, was that spectro1d assigned the incorrect identification to emission features.

Umag
The SDSS DR7 u-band filter magnitude of the quasar (not corrected for Galactic extinction). The effective wavelengths of the u, g, r, i, and z bandpasses are 3541, 4653, 6147, 7461, and 8904 Angstroms, respectively (for an alpha = -0.5 power-law spectral energy distribution using the definition of effective wavelength given in Schneider et al. (1983, ApJ, 269, 352). The photometric measurements are reported as arcsinh magnitudes (Lupton et al. 1999, AJ, 118, 1406) and are normalized (to ~3% accuracy) to the AB-magnitude system (Oke & Gunn 1983, ApJ, 266, 713). Unlike the previous editions of the SDSS quasar catalog, in this release the authors use the "ubercalibration" photometric calibrations of Padmanabhan et al. (2008, ApJ, 674, 1217). A value of 0.000 indicates that the magnitude could not be retrieved from the SDSS database.

Umag_Error
The error in the SDSS DR7 PSF u-band filter magnitude of the quasar (not corrected for Galactic extinction).

Gmag
The SDSS DR7 PSF g-band filter magnitude of the quasar (not corrected for Galactic extinction). The effective wavelengths of the u, g, r, i, and z bandpasses are 3541, 4653, 6147, 7461, and 8904 Angstroms, respectively (for an alpha = -0.5 power-law spectral energy distribution using the definition of effective wavelength given in Schneider et al. (1983, ApJ, 269, 352). The photometric measurements are reported as arcsinh magnitudes (Lupton et al. 1999, AJ, 118, 1406) and are normalized (to ~3% accuracy) to the AB-magnitude system (Oke & Gunn 1983, ApJ, 266, 713). Unlike the previous editions of the SDSS quasar catalog, in this release the authors use the "ubercalibration" photometric calibrations of Padmanabhan et al. (2008, ApJ, 674, 1217). A value of 0.000 indicates that the magnitude could not be retrieved from the SDSS database.

Gmag_Error
The error in the SDSS DR7 PSF g-band filter magnitude of the quasar (not corrected for Galactic extinction).

Rmag
The SDSS DR7 PSF r-band filter magnitude of the quasar (not corrected for Galactic extinction). The effective wavelengths of the u, g, r, i, and z bandpasses are 3541, 4653, 6147, 7461, and 8904 Angstroms, respectively (for an alpha = -0.5 power-law spectral energy distribution using the definition of effective wavelength given in Schneider et al. (1983, ApJ, 269, 352). The photometric measurements are reported as arcsinh magnitudes (Lupton et al. 1999, AJ, 118, 1406) and are normalized (to ~3% accuracy) to the AB-magnitude system (Oke & Gunn 1983, ApJ, 266, 713). Unlike the previous editions of the SDSS quasar catalog, in this release the authors use the "ubercalibration" photometric calibrations of Padmanabhan et al. (2008, ApJ, 674, 1217). A value of 0.000 indicates that the magnitude could not be retrieved from the SDSS database.

Rmag_Error
The error in the SDSS DR7 PSF r-band filter magnitude of the quasar (not corrected for Galactic extinction).

Imag
The SDSS DR7 PSF i-band filter magnitude of the quasar (not corrected for Galactic extinction). The effective wavelengths of the u, g, r, i, and z bandpasses are 3541, 4653, 6147, 7461, and 8904 Angstroms, respectively (for an alpha = -0.5 power-law spectral energy distribution using the definition of effective wavelength given in Schneider et al. (1983, ApJ, 269, 352). The photometric measurements are reported as arcsinh magnitudes (Lupton et al. 1999, AJ, 118, 1406) and are normalized (to ~3% accuracy) to the AB-magnitude system (Oke & Gunn 1983, ApJ, 266, 713). Unlike the previous editions of the SDSS quasar catalog, in this release the authors use the "ubercalibration" photometric calibrations of Padmanabhan et al. (2008, ApJ, 674, 1217). A value of 0.000 indicates that the magnitude could not be retrieved from the SDSS database.

Imag_Error
The error in the SDSS DR7 PSF i-band filter magnitude of the quasar (not corrected for Galactic extinction).

Zmag
The SDSS DR7 PSF z-band filter magnitude of the quasar (not corrected for Galactic extinction). The effective wavelengths of the u, g, r, i, and z bandpasses are 3541, 4653, 6147, 7461, and 8904 Angstroms, respectively (for an alpha = -0.5 power-law spectral energy distribution using the definition of effective wavelength given in Schneider et al. (1983, ApJ, 269, 352). The photometric measurements are reported as arcsinh magnitudes (Lupton et al. 1999, AJ, 118, 1406) and are normalized (to ~3% accuracy) to the AB-magnitude system (Oke & Gunn 1983, ApJ, 266, 713). Unlike the previous editions of the SDSS quasar catalog, in this release the authors use the "ubercalibration" photometric calibrations of Padmanabhan et al. (2008, ApJ, 674, 1217). A value of 0.000 indicates that the magnitude could not be retrieved from the SDSS database.

Zmag_Error
The error in the SDSS DR7 PSF z-band filter magnitude of the quasar (not corrected for Galactic extinction).

Gal_Abs_U
The Galactic extinction in the u band A_u based on the maps of Schlegel et al. (1998, ApJ, 500, 525). For an R_V = 3.1 absorbing medium, the extinctions in the SDSS bands can be expressed as A_x = C_x E(B-V), where x is the filter (ugriz) and values of C_x are 5.155, 3.793, 2.751, 2.086, and 1.479 for ugriz, respectively (A_g, A_r, A_i, and A_z are 0.736, 0.534, 0.405, and 0.287 times A_u).

Log_NH_Gal
The logarithm of the Galactic neutral hydrogen column density along the line of sight to the quasar, in atoms cm-2. These values were estimated via interpolation of the 21 cm data from Stark et al. (1992, ApJS, 79, 77), using the COLDEN software provided by the Chandra X-Ray Center. Errors associated with the interpolation are typically expected to be less than ~ 1020 cm-2 (e.g., see Section 5 of Elvis et al. 1994, ApJS, 95, 413).

Mag_20_cm
If there is a source in the FIRST catalog (White et al. 1998, ApJ, 475, 479) within 2.0" of the quasar position, this parameter contains the FIRST peak flux density at 20 cm f_nu encoded as an AB magnitude, AB = -2.5 log(f_nu/3631 Jy), (see Ivezic et al. 2002, AJ, 124, 2364). An entry of 0.000 indicates no match to a FIRST source; an entry of -1.000 indicates that the object does not lie in the region covered by the final catalog of the FIRST survey. The catalog contains 8630 FIRST matches; 6865 (6.5%) of the DR7 quasars lie outside of the FIRST area.

Flux_20_cm
The FIRST peak flux density at 20 cm, in mJy, of the source in the FIRST catalog (White et al. 1998, ApJ, 475, 479) within 2.0" of the quasar position. This parameter was calculated by the HEASARC from the mag_20_cm parameter (q.v.). An entry of 0.000 indicates no match to a FIRST source; an entry of -1.000 indicates that the object does not lie in the region covered by the final catalog of the FIRST survey. The catalog contains 8630 FIRST matches; 6865 (6.5%) of the DR7 quasars lie outside of the FIRST area.

SNR_20_cm
The signal-to-noise ratio of the FIRST source whose flux is given in the flux_20_cm parameter.

SDSS_FIRST_Offset
The separation between the SDSS and FIRST coordinates of the quasar (in arcseconds).

RASS_Count_Rate
The vignetting-corrected count rate (counts s-1) in the broad-energy band (0.1-2.4 keV) in the RASS Faint Source Catalog (Voges et al. 2000, IAUC 7432) or the RASS Bright Source Catalog (Voges et al. 1999, A&A, 349, 389). The matching radius was set to 30". A null entry for this parameter indicates no X-ray detection. There are 5377 RASS matches in the DR7 catalog.

RASS_SNR
The signal-to-noise ratio of the ROSAT measurement.

SDSS_RASS_Offset
The separation between the SDSS and RASS coordinates (in arcseconds).

Jmag_2MASS
The J magnitude from the Two Micron All Sky Survey (2MASS; Skrutskie et al. 2006, AJ, 131, 1163) All-Sky Data Release Point Source Catalog using a matching radius of 2.0". A nondetection by 2MASS is indicated by a null value. Note that the 2MASS measurements are Vega-based, not AB, magnitudes. The catalog contains 53,564 2MASS matches.

Jmag_2MASS_Error
The error in the J magnitude from the Two Micron All Sky Survey (2MASS).

Hmag_2MASS
The H magnitude from the Two Micron All Sky Survey (2MASS; Skrutskie et al. 2006, AJ, 131, 1163) All-Sky Data Release Point Source Catalog using a matching radius of 2.0". A nondetection by 2MASS is indicated by a null value. Note that the 2MASS measurements are Vega-based, not AB, magnitudes. The catalog contains 53,564 2MASS matches.

Hmag_2MASS_Error
The error in the H magnitude from the Two Micron All Sky Survey (2MASS).

Kmag_2MASS
The K magnitude from the Two Micron All Sky Survey (2MASS; Skrutskie et al. 2006, AJ, 131, 1163) All-Sky Data Release Point Source Catalog using a matching radius of 2.0". A nondetection by 2MASS is indicated by a null value. Note that the 2MASS measurements are Vega-based, not AB, magnitudes. The catalog contains 53,564 2MASS matches.

Kmag_2MASS_Error
The error in the K magnitude from the Two Micron All Sky Survey (2MASS).

SDSS_2MASS_Offset
The separation between the SDSS and 2MASS coordinates (in arcseconds).

TwoMASS_Flag
The 2MASS flag 2Flgs = 9*JFLAG + 3*HFLAG + KGLAG where JFLAG, HFLAG and KFLAG are the flags for the individual J, H and K filters and can have the following possible values:

    0 = no detection
    1 = catalog match
    2 = new photometry
  

Abs_Imag
The absolute magnitude in the SDSS i band calculated by correcting for Galactic extinction and assuming H_0 = 70 km s-1 Mpc-1, Omega_M = 0.3, Omega_Lambda = 0.7, and a power-law (frequency) continuum index of -0.5.

GI_Color_Offset
The Delta(g - i) color difference, which is the difference in the Galactic extinction-corrected (g - i) for the quasar and that of the mode of the distribution of quasars at that redshift. If Delta (g - i) is not defined for the quasar, the parameter contains a value of -9.000. See Section 5 of the published reference paper for a description of this quantity.

Morphology_Flag
This flag parameter contains morphological information. If the SDSS photometric pipeline classified the image of the quasar as a point source, the catalog value is 0; if the quasar is extended, the catalog value is 1.

Scienceprimary_Flag
The SDSS SCIENCEPRIMARY flag, which indicates whether the spectrum was taken as a normal science spectrum (SCIENCEPRIMARY = 1) or for another purpose (SCIENCEPRIMARY = 0). The latter category contains quality assurance and calibration spectra, or spectra of objects located outside of the nominal survey area. Over 90% of the DR7 entries (95,630 objects) are SCIENCEPRIMARY = 1.

Mode_Flag
This flag provides information for blends and/or overlapping scans on whether the photometric object is designated as the primary object (1), a secondary observation (2), or a "family" observation (3; these are blended objects that have not been deblended).

Uts_Flag
The "uniform target selection" flag, either 0 or 1; a value of 1 indicates that the object was identified as a primary quasar target with the final target selection algorithm as given by Richards et al. (2002, AJ, 123, 2945), while a value of 0 means that the object was not selected with the final algorithm. The objects with a value of 1 constitute a statistical sample.

Best_TS_Flag
The 32-bit SDSS target-selection flag from BEST processing (PRIMTARGET; see Table 26 in Stoughton et al. [2002, AJ, 123, 485] for details); this is the flag produced by running the selection algorithm of Richards et al. (2002, AJ, 123, 2945) on the most recent processing of the image data.

Best_Lzq_Flag
The low-z quasar target flag value derived from the spectroscopic target selection breakdown (BEST) for each object. The target selection flag (the best_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Best_Hzq_Flag
The high-z quasar target flag value derived from the spectroscopic target selection breakdown (BEST) for each object. The target selection flag (the best_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Best_FIRST_Flag
The FIRST target flag value derived from the spectroscopic target selection breakdown (BEST) for each object. The target selection flag (the best_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Best_ROSAT_Flag
The ROSAT target flag value derived from the spectroscopic target selection breakdown (BEST) for each object. The target selection flag (the best_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Best_Serendip_Flag
The serendipitous target flag value derived from the spectroscopic target selection breakdown (BEST) for each object. The target selection flag (the best_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Best_Star_Flag
The star target flag value derived from the spectroscopic target selection breakdown (BEST) for each object. The target selection flag (the best_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Best_Galaxy_Flag
The galaxy target flag value derived from the spectroscopic target selection breakdown (BEST) for each object. The target selection flag (the best_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Imaging_Run_Number
The SDSS imaging run number of the BEST photometric observation used in the catalog. The MJD is given as an integer; all observations on a given night have the same integer MJD (and, because of the observatory's location, the same UT date).

Imaging_Date
The date of the BEST imaging observation used in the catalog (converted by the HEASARC from Modified Julian Date (MJD) to actual date). The original MJD was given as an integer; all observations on a given night have the same integer MJD (and, because of the observatory's location, the same date).

Spect_Date
The date of the spectroscopic observation (converted by the HEASARC from Modified Julian Date (MJD) to actual date) used to determine the redshift. The original MJD was given as an integer; all observations on a given night have the same integer MJD (and, because of the observatory's location, the same date). The date, spectroscopic plate number, and spectroscopic fiber number are unique for each spectrum, and can be used to retrieve the digital spectra from the public SDSS database.

Spect_Plate_Number
The spectroscopic plate number of the spectroscopic observation used to determine the redshift. The date, spectroscopic plate number, and spectroscopic fiber number are unique for each spectrum, and can be used to retrieve the digital spectra from the public SDSS database. #

Spect_Fiber_Number
The spectroscopic fiber number of the spectroscopic observation used to determine the redshift. The date, spectroscopic plate number, and spectroscopic fiber number are unique for each spectrum, and can be used to retrieve the digital spectra from the public SDSS database.

Rerun_Number
The SDSS photometric processing rerun number. See Stoughton et al. (2002, AJ, 123, 485) for a description of this parameter.

Camera_Column_Number
The number of the SDSS camera column (1-6) which contained the image of the object. See Stoughton et al. (2002, AJ, 123, 485) for a description of this parameter.

Frame_Number
The SDSS field number of the run containing the object. See Stoughton et al. (2002, AJ, 123, 485) for a description of this parameter.

Object_Number
The SDSS object identification number within the given SDSS field. See Stoughton et al. (2002, AJ, 123, 485) for a description of this parameter.

Target_TS_Flag
The 32-bit SDSS target selection flag from the TARGET processing, i.e., the value that was used when the spectroscopic plate was drilled. This may not match the BEST target selection flag because different versions of the selection algorithm were used, the selection was done with different image data (superior quality data of the field were obtained after the spectroscopic observations were completed), or different processings of the same data were used. Objects with no TARGET flag were either identified as quasars as a result of quality assurance observations and/or from special plates with somewhat different targeting criteria (see Adelman-McCarthy et al. 2006, ApJS, 162, 38).

Target_Lzq_Flag
The low-z quasar target flag value derived from the spectroscopic target selection breakdown (TARGET) for each object. The target selection flag (the target_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Target_Hzq_Flag
The high-z quasar target flag value derived from the spectroscopic target selection breakdown (TARGET) for each object. The target selection flag (the target_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Target_FIRST_Flag
The FIRST target flag value derived from the spectroscopic target selection breakdown (TARGET) for each object. The target selection flag (the target_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Target_ROSAT_Flag
The ROSAT target flag value derived from the spectroscopic target selection breakdown (TARGET) for each object. The target selection flag (the target_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Target_Serendip_Flag
The serendipity flag value derived from the spectroscopic target selection breakdown (TARGET) for each object. The target selection flag (the target_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Target_Star_Flag
The star target flag value derived from the spectroscopic target selection breakdown (TARGET) for each object. The target selection flag (the target_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Target_Galaxy_Flag
The galaxy target flag value derived from the spectroscopic target selection breakdown (TARGET) for each object. The target selection flag (the target_ts_flag parameter) is decoded for seven groups: low-redshift quasar, high-redshift quasar, FIRST, ROSAT, serendipity, star, and galaxy. An entry of 1 indicates that the object satisfied the given criterion (see Stoughton et al. 2002, AJ, 123, 485). Note that an object can be, and often is, targeted by more than one selection algorithm.

Target_Umag
The SDSS DR7 u-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Umag_Error
The error in the SDSS DR7 u-band PSF magnitude.

Target_Gmag
The SDSS DR7 g-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Gmag_Error
The error in the SDSS DR7 g-band PSF magnitude.

Target_Rmag
The SDSS DR7 r-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Rmag_Error
The error in the SDSS DR7 r-band PSF magnitude.

Target_Imag
The SDSS DR7 i-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Imag_Error
The error in the SDSS DR7 i-band PSF magnitude.

Target_Zmag
The SDSS DR7 z-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Zmag_Error
The error in the SDSS DR7 z-band PSF magnitude

Best_Object_ID
The BEST object identification is a 64-bit integer that uniquely describes the BEST imaging observation that is listed in the catalog.

Spect_Object_ID
The spectroscopic object identification is a 64-bit integer that uniquely describes the spectroscopic observation that is listed in the catalog.

Alt_Name
The name of the object in the NASA/IPAC Extragalactic Database (NED), where "SDSS" designates a previously published SDSS object. If there is a source in the NED quasar database within 5.0" of the quasar position, the NED object name is given in this column. 101,945 (96.4%) of the 105,783 entries in the DR7 quasar catalog were either not listed in NED or were recorded as an SDSS discovery in the NED database. (Occasionally, NED will list the SDSS name for objects that were not discovered by the SDSS).


Contact Person

Questions regarding the SDSSQUASAR database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 7-Jun-2010