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SDSSQUASAR: Help

SDSSQUASAR - Sloan Digital Sky Survey Quasar Catalog (5th Data Release)


Overview

This table contains the fourth edition of the Sloan Digital Sky Survey (SDSS) Quasar Catalog. The catalog contains 77,429 objects; this is an increase of over 30,000 entries since the previous edition. The catalog consists of the objects in the SDSS Fifth Data Release 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 ~ 5740 deg^2. The quasar redshifts range from 0.08 to 5.41, with a median value of 1.48; the catalog includes 891 quasars at redshifts greater than 4, of which 36 are at redshifts greater than 5. Approximately half of the catalog quasars have i < 19, nearly all have i < 21. For each object the catalog presents positions accurate to better than 0.2" 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 public database using the information provided in the catalog. Approximately 96% of the objects in the catalog were discovered by the SDSS.

Catalog Bibcode

2007AJ....134..102S

References

The Sloan Digital Sky Survey Quasar Catalog IV (5th Data Release)
    Schneider D.P., Hall P.B., Richards G.T., Strauss M.A.,
    Vanden Berk D.E., Anderson S.F., Brandt W.N., Fan X., Jester S.,
    Gray J., Gunn J.E., SubbaRao M.U., Thakar A.R., Stoughton C.,
    Szalay A.S., Yanny B., York D.G., Bahcall N.A., Barentine J.,
    Blanton M.R., Brewington H., Brinkmann J., Brunner R.J.,
    Castander F.J., Csabai I., Frieman J.A., Fukugita M., Harvanek M.,
    Hogg D.W., Ivezic Z., Kent S.M., Kleinman S.J., Knapp G.R., Kron R.G.,
    Krzesinski J., Long D.C., Lupton R.H., Nitta A., Pier J.R., Saxe D.H.,
    Shen Y., Snedden S.A., Weinberg D.H., Wu J.
   <Astron. J., 134, 102-117 (2007)>
   =2007AJ....134..102S

Provenance

This table was created by the HEASARC in September 2007 based on the electronic version of Table 2 from the above paper obtained from the electronic AJ 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, which was given as the logarithm of the count rate in the published catalog, is given herein as the actual count rate value CR rather than the log of CR.

Parameters

Name
The J2000 position-based DR5 object designation, given in the format 'SDSS Jhhmmss.ss+ddmmss.s'. The coordinates in the object name follow 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 vast majority of the objects are accurate to 0.1" rms or better in each coordinate: the largest expected errors are 0.2". 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), and have an rms accuracy of 0.045" per coordinate.

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 vast majority of the objects are accurate to 0.1" rms or better in each coordinate: the largest expected errors are 0.2". 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), and have an rms accuracy of 0.045" per coordinate.

LII
The Galactic Longitude of the quasar.

BII
The Galactic Latitude of the quasar.

Redshift
The quasar redshift. A total of 863 of the SDSS Catalog Archive Server (CAS) redshifts were revised during the authors' visual inspection. A detailed description of the redshift measurements is given in Section 4.10 of Stoughton et al. (2002, AJ, 123, 485). A comparison of 299 quasars observed at multiple epochs by the SDSS (Wilhite et al. 2005, ApJ, 633, 638) found an rms difference of 0.006 in the measured redshifts for a given object. It is well known that the redshifts of individual broad emission lines in quasars exhibit significant offsets from their systemic redshifts; the catalog redshifts attempt to correct for this effect in the ensemble average (see Stoughton et al. 2002).

Umag
The SDSS DR5 PSF u-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry. Some of the relevant imaging scans, such as special scans through M31 (see the DR4 and DR5 papers), were never loaded into the CAS; therefore, BEST photometry is not available for them. Thus, there are 134 quasars that have entries of "0.000" for their BEST photometric measurements.

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 in the natural system of the SDSS camera, and the magnitudes are normalized to the AB system (Oke & Gunn 1983, ApJ, 266, 713). The measurements are reported as arcsinh magnitudes; see Adelman-McCarthy et al. (2007, ApJS, in press) for additional discussion and references for the accuracy of the photometric measurements.

Umag_Error
The error in the SDSS DR5 PSF u-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry.

Gmag
The SDSS DR5 PSF g-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry. Some of the relevant imaging scans, such as special scans through M31 (see the DR4 and DR5 papers), were never loaded into the CAS; therefore, BEST photometry is not available for them. Thus, there are 134 quasars that have entries of "0.000" for their BEST photometric measurements.

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 in the natural system of the SDSS camera, and the magnitudes are normalized to the AB system (Oke & Gunn 1983, ApJ, 266, 713). The measurements are reported as arcsinh magnitudes; see Adelman-McCarthy et al. (2007, ApJS, in press) for additional discussion and references for the accuracy of the photometric measurements.

Gmag_Error
The error in the SDSS DR5 PSF g-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry.

Rmag
The SDSS DR5 PSF r-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry. Some of the relevant imaging scans, such as special scans through M31 (see the DR4 and DR5 papers), were never loaded into the CAS; therefore, BEST photometry is not available for them. Thus, there are 134 quasars that have entries of "0.000" for their BEST photometric measurements.

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 in the natural system of the SDSS camera, and the magnitudes are normalized to the AB system (Oke & Gunn 1983, ApJ, 266, 713). The measurements are reported as arcsinh magnitudes; see Adelman-McCarthy et al. (2007, ApJS, in press) for additional discussion and references for the accuracy of the photometric measurements.

Rmag_Error
The error in the SDSS DR5 PSF r-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry.

Imag
The SDSS DR5 PSF i-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry. Some of the relevant imaging scans, such as special scans through M31 (see the DR4 and DR5 papers), were never loaded into the CAS; therefore, BEST photometry is not available for them. Thus, there are 134 quasars that have entries of "0.000" for their BEST photometric measurements.

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 in the natural system of the SDSS camera, and the magnitudes are normalized to the AB system (Oke & Gunn 1983, ApJ, 266, 713). The measurements are reported as arcsinh magnitudes; see Adelman-McCarthy et al. (2007, ApJS, in press) for additional discussion and references for the accuracy of the photometric measurements.

Imag_Error
The error in the SDSS DR5 PSF i-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry.

Zmag
The SDSS DR5 PSF z-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry. Some of the relevant imaging scans, such as special scans through M31 (see the DR4 and DR5 papers), were never loaded into the CAS; therefore, BEST photometry is not available for them. Thus, there are 134 quasars that have entries of "0.000" for their BEST photometric measurements.

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 in the natural system of the SDSS camera, and the magnitudes are normalized to the AB system (Oke & Gunn 1983, ApJ, 266, 713). The measurements are reported as arcsinh magnitudes; see Adelman-McCarthy et al. (2007, ApJS, in press) for additional discussion and references for the accuracy of the photometric measurements.

Zmag_Error
The error in the SDSS DR5 PSF z-band filter magnitude of the quasar (not corrected for Galactic extinction) from BEST photometry.

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 ~ 10^20 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 6226 FIRST matches; 5729 DR5 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 6226 FIRST matches; 5729 DR5 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).

First_Flag_1
In cases when the FIRST counterpart to an SDSS source is extended, the FIRST catalog position of the source may differ by more than 2" from the optical position. A value of 1 for this flag parameter indicates that no matching FIRST source was found within 2" of the optical position, but that there is significant detection (larger than 3 sigma) of FIRST flux at the optical position. This is the case for 2440 SDSS quasars. Otherwise this parameter is set to 0.

First_Flag_2
A value of 1 for this flag parameter identifies one of the 1596 sources with a FIRST match within 2" (either a point source or extended emission) that also have at least one FIRST counterpart located between 2.0" (the SDSS FIRST matching radius) and 30" of the optical position. Based on the average FIRST source surface density of 90 deg^-2, the authors expect 50-60 of these matches to be chance superpositions.

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 4133 RASS matches in the DR5 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 9824 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 9824 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 9824 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).

Abs_Imag
The absolute magnitude in the 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 mean of the quasars at that redshift. If Delta (g - i) is not defined for the quasar, which occurs for objects at either z < 0.12 or z > 5.12, the parameter contains a value of -9.000. See Section 5.2 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 DR5 entries (69,762 objects) are SCIENCEPRIMARY = 1.

Mode_Flag
This flag provides information on whether the photometric object is designated PRIMARY (1), SECONDARY (2), or FAMILY (3; these are blended objects that have not been deblended). During target selection, only PRIMARY objects are considered (except on occasion for objects located in fields that are not part of the nominal survey area); however, differences between TARGET and BEST photometric pipeline versions make it possible that the BEST photometric object belonging to a spectrum is either not detected at all or is a nonprimary object (see Section 3.1 of the reference paper). Over 99% of the catalog entries are PRIMARY; 613 quasars are SECONDARY, and 9 are FAMILY. There are 124 quasars with an entry of 0: each of these is an object that lacks BEST photometry. For statistical analysis, one should use only PRIMARY objects; SECONDARY and FAMILY objects are included in the catalog for the sake of completeness with respect to confirmed quasars.

Uts_Flag
The "uniform selection" flag, either 0 or 1; a value of 1 indicates that the object was identified as a primary quasar target (37,574 catalog entries) with the final target selection algorithm as given by Richards et al. (2002, AJ, 123, 2945). These objects 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 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 Run Number for Photometric Measurements

Imaging_Date
The date of the photometric 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 DR5 u-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Umag_Error
The error in the SDSS DR5 u-band PSF magnitude.

Target_Gmag
The SDSS DR5 g-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Gmag_Error
The error in the SDSS DR5 g-band PSF magnitude

Target_Rmag
The SDSS DR5 r-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Rmag_Error
The error in the SDSS DR5 r-band PSF magnitude

Target_Imag
The SDSS DR5 i-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Imag_Error
The error in the SDSS DR5 i-band PSF magnitude

Target_Zmag
The SDSS DR5 z-band PSF magnitude (not corrected for Galactic reddening) from TARGET photometry.

Target_Zmag_Error
The error in the SDSS DR5 z-band PSF magnitude

Spect_Id_Flag
The spectroscopic identification flag, being 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). 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. The NED quasar database contains over 100,000 objects. 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.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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