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SDSSQUASAR - Sloan Digital Sky Survey Quasar Catalog (7th Data Release) |
HEASARC Archive |
Much more information on the SDSS is available at the project's web site at http://www.sdss.org/.
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
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).