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SDSSQUASAR - Sloan Digital Sky Survey Quasar Catalog (Twelfth Data Release: DR12Q) |
HEASARC Archive |
Overview
This table contains the Data Release 12 Quasar Catalog (DR12Q) from the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III (SDSS-III). This catalog includes all SDSS-III/BOSS objects that were spectroscopically targeted as quasar candidates during the full survey and that are confirmed as quasars via visual inspection of the spectra, have luminosities M_i_[z=2] < -20.5 (in a LambdaCDM cosmology with H0 = 70 km/s/Mpc, OmegaM = 0.3, and OmegaLambda = 0.7), and either display at least one emission line with a full width at half maximum (FWHM) larger than 500 km/s or, if not, have interesting/complex absorption features. The catalog also includes previously known quasars (mostly from SDSS-I and II) that were re-observed by BOSS. The catalog contains 297,301 quasars (272,026 are new discoveries since the beginning of SDSS-III) detected over 9376 deg2 with robust identification and redshift measured by a combination of principal component eigenspectra. The number of quasars with z > 2.15 (184,101, of which 167,742 are new discoveries) is about an order of magnitude greater than the number of z > 2.15 quasars known prior to BOSS. Redshifts and FWHMs are provided for the strongest emission lines (C IV, C III], Mg II). The catalog identifies 29,580 broad absorption line quasars and their characteristics are listed in the file dr12qbal.dat that is available at the CDS (http://cdsarc.u-strasbg.fr/ftp/cats/VII/279/). For each object, the catalog presents five-band (u, g, r, i, z) CCD-based photometry with typical accuracy of 0.03 mag together with some information on the optical morphology and the selection criteria. When available, the catalog also provides information on the optical variability of quasars using SDSS and Palomar Transient Factory multi-epoch photometry. The catalog also contains X-ray, ultraviolet, near-infrared, and radio emission properties of the quasars, when available, from other large-area surveys. The calibrated digital spectra, covering the wavelength region 3600-10,500 Angstrom at a spectral resolution in the range 1300 < R < 2500, can be retrieved from the SDSS Catalog Archive Server at http://www.sdss.org/dr12/data_access/. In their paper, the authors also provide a supplemental list of an additional 4,841 quasars that have been identified serendipitously outside of the superset defined to derive the main quasar catalog, available as the file dr12qsp.dat that is available at the CDS (http://cdsarc.u-strasbg.fr/ftp/cats/VII/279/).This table contains the final quasar catalog of the SDSS-III/BOSS survey resulting from five years of observations. The catalog, which the authors call "DR12Q", contains 297,301 quasars, 184,101 of which have z > 2.15. the authors provide robust identification from visual inspection and refined redshift measurements based on the result of a principal component analysis of the spectra. The present catalog contains about 80% more quasars than their previous release (Paris et al., 2014, "DR10Q", CDS Cat. VII/270).
In SDSS-III, all fluxes in the 5 SDSS bands (u, g, r, i and z) are expressed in terms of "nanomaggies" (nMgy), which are a convenient linear unit. These quantities are related to standard AB magnitudes thus: an object with a flux F given in nMgy has a Pogson magnitude (on the AB scale) m = [22.5 mag] - 2.5*log10(F). A flux of 1 Mgy is therefore close to 3631 Jy, and 1 nMgy = ~3.631 uJy (µJy).
Catalog Bibcode
2017A&A...597A..79PReferences
The Sloan Digital Sky Survey Quasar Catalog: Twelfth data release.
Paris I., Petitjean P., Ross N.P., Myers A.D., Aubourg E., Streblyanska A.,
Bailey S., Armengaud E., Palanque-Delabrouille N., Yeche C., Hamann F.,
Strauss M.A., Albareti F.D., Bovy J., Bizyaev D., Brandt W.N., Brusa M.,
Buchner J., Comparat J., Croft R.A.C., Dwelly T., Fan X., Font-Ribera A.,
Ge J., Georgakakis A., Hall P.B., Jiang L., Kinemuchi K., Malanushenko E.,
Malanushenko V., Mcmahon R.G., Menzel M.-L., Merloni A., Nandra K.,
Noterdaeme P., Oravetz D., Pan K., Pieri M.M., Prada F., Salvato M.,
Schlegel D.J., Schneider D.P., Simmons A., Viel M., Weinberg D.H., Zhu L.
<Astron. Astrophys., 597, A79 (2017)>
=2017A&A...597A..79P (SIMBAD/NED BibCode)
=2017yCat.7278....0P
Provenance
This table was updated to DR12Q in July 2017 based on CDS Catalog VII/279 file dr12q.dat.HEASARC Implementation
If a quasar in DR12Q was observed spectroscopically more than once during the survey, the properties as derived from the best (highest signal-to-noise) spectrum are the ones cited in the present table. The plate number, date, fiber number and median signal-to-noise ratio over the whole spectrum of the additional lower-quality observations of these quasars are not included in the HEASARC implementation of the DR12Q table but can be found in the original CDS version at http://cdsarc.u-strasbg.fr/ftp/cats/VII/279/dr12q.dat.gz.Parameters
Name
The SDSS-DR12 object designation, given by the J2000.0 position-based format
"SDSS JHHMMSS.ss+DDMMSS.s", as corrected by the CDS (some of the original
names were erroneous). The coordinates in the object name follow IAU
convention and are truncated, not rounded.
Orig_Name
The original SDSS-DR12 object designation ("SDSS JHHMMSS.ss+DDMMSS.s") in the
table as supplied to the CDS.
RA
The Right Ascension of the quasar in the selected equinox. This was given in
J2000.0 decimal degrees to a precision of 10-6 degrees in the original
table. The astrometry is from SDSS-DR12 (see Alam et al. 2015, ApJS, 219, 12).
Dec
The Declination of the quasar in the selected equinox. This was given in
J2000.0 decimal degrees to a precision of 10-6 degrees in the original
table. The astrometry is from SDSS-DR12 (see Alam et al. 2015, ApJS, 219, 12).
LII
The Galactic Longitude of the quasar.
BII
The Galactic Latitude of the quasar.
Thing_ID
The 64-bit integer that uniquely describes the objects that are listed in the
SDSS (photometric and spectroscopic) catalogs (THING_ID).
Spect_Plate_Number
The SDSS spectroscopic plate number of the observation. This is one of 3
pieces of information about the spectroscopic observation (spectroscopic
plate number, modified Julian Date, and spectroscopic fiber number) that were
used to determine the characteristics of the spectrum. These three numbers
are unique for each spectrum, and can be used to retrieve the digital spectra
from the public SDSS database. When an object has been observed more than
once, the authors selected the best quality spectrum as defined by the SDSS
pipeline (Bolton et al. 2012, AJ, 144, 144), i.e. with SPECPRIMARY = 1.
Spect_Date
The SDSS spectroscopic date of the observation. This is one of 3 pieces of
information about the spectroscopic observation (the spectroscopic plate
number, this date represented as a Modified Julian Date -- the HEASARC xTime
web tool can be used to find the MJD corresponding to this YYYY-MM-DD date --
and the spectroscopic fiber number) that were used to determine the
characteristics of the spectrum. These three numbers are unique for each
spectrum, and can be used to retrieve the digital spectra from the public
SDSS database. When an object has been observed more than once, the authors
selected the best quality spectrum as defined by the SDSS pipeline (Bolton et
al. 2012, AJ, 144, 144), i.e. with SPECPRIMARY = 1.
Spect_Fiber_Number
The SDSS fiber number of the observation. This is one of 3 pieces of
information about the spectroscopic observation (spectroscopic plate number,
modified Julian Date, and spectroscopic fiber number) that were used to
determine the characteristics of the spectrum. These three numbers are unique
for each spectrum, and can be used to retrieve the digital spectra from the
public SDSS database. When an object has been observed more than once, the
authors selected the best quality spectrum as defined by the SDSS pipeline
(Bolton et al. 2012, AJ, 144, 144), I.e. with SPECPRIMARY = 1.
VI_Redshift
The redshift of the quasar obtained from the visual inspection, Z_VI (see
Sections 3.1 of the reference paper for more details).
Pipeline_Redshift
The redshift of the quasar from the SDSS BOSS pipeline (Bolton et al. 2012,
AJ, 144, 144).
Pipeline_Redshift_Error
The error in the BOSS pipeline redshift estimate.
The meaning of error codes -4, -5, -6 is not known to the HEASARC.
Pipeline_Redshift_Flag
The ZWARNING flag from the pipeline. ZWARNING > 0 indicates uncertain results
in the redshift-fitting code (Bolton et al. 2012, AJ, 144, 144). This flag is
made of the following bits:
1 [0] = sky fiber
2 [1] = too little wavelength coverage
4 [2] = chi-squared of best fit is too close to that of second best
8 [3] = synthetic spectrum is negative
16 [4] = fraction of points more than 5{sigma} away from best model
is too large (>5%)
32 [5] = chi-squared minimum at edge of the redshift fitting range
64 [6] = a QSO line exhibits negative emission (triggered only in QSO
spectra if CIV, CIII, MgII, H{beta}, or H{alpha} has
lineArea+3{sigma}(lineArea)<0)
128 [7] = the fiber was unplugged or broken, so no spectrum obtained
PCA_Redshift
An automatic redshift estimate Z_PCA for the quasar which uses a linear
combination of four principal components (see Section 4 of Paris et al. 2012,
A&A, 548, A66 for details). When the velocity difference between the
automatic PCA and visual inspection redshift estimates is larger than 5,000 km
s-1, this PCA redshift is set to null (-1 in the original table).
PCA_Redshift_Error
The error in the automatic PCA redshift estimate for the quasar. If the PCA
redshift is set to null, the associated error is also set to null (-1 in the
original table).
PCA_Continuum_Quality
An estimator of the PCA continuum quality (between 0 and 1) as given in Eq.
(11) of Paris et al. (2011, A&A, 530, A50).
C_IV_Redshift
The redshift of the quasar measured from the C IV emission line from a linear
combination of five principal components (see Paris et al. 2012, A&A, 548,
A66). The line redshift is estimated using the maximum of each emission line,
contrary to Z_PCA (the pca_redshift parameter) that is a global estimate
using all the information available in a given spectrum.
C_III_Redshift
The redshift of the quasar measured from the the C III emission line complex
from a linear combination of five principal components (see Paris et al.
2012, A&A, 548, A66). The line redshift is estimated using the maximum of
each emission line, contrary to Z_PCA (the pca_redshift parameter) that is a
global estimate using all the information available in a given spectrum.
Mg_II_Redshift
The redshift of the quasar measured from the Mg II emission line from a
linear combination of five principal components (see Paris et al. 2012, A&A,
548, A66). The line redshift is estimated using the maximum of each emission
line, contrary to Z_PCA (the pca_redshift parameter) that is a global
estimate using all the information available in a given spectrum.
Morphology_Flag
The morphological information flag SDSS_MORPHO for the quasar: objects
classified as point sources by the SDSS photometric pipeline have SDSS_MORPHO
= 0 while extended quasars have SDSS_MORPHO = 1. The vast majority of the
quasars included in the present catalog are unresolved (SDSS_MORPHO = 0) as
it is a requirement of the main quasar target selection (Ross et al. 2012,
ApJS, 199, 3).
Boss_TS_Flag
The BOSS target selection flag for the quasar. The main target selection
information is tracked with the BOSS_TARGET1 flag bits (see Table 2 in Ross
et al. 2012, ApJS, 199, 3 for a full description).
Anc_TS_Flag_1
The ancillary target selection flag 1 (ANCILLARY_TARGET1) for the quasar.
Ancillary program target selection is tracked with the ANCILLARY_TARGET1 and
ANCILLARY_TARGET2 flag bits. The bit values and the corresponding program
names are listed in Dawson et al. (2013, AJ, 145, 10), Alam et al. (2015,
ApJS, 219, 12), and Appendix B of the reference paper.
Anc_TS_Flag_2
The ancillary target selection flag 2 (ANCILLARY_TARGET2) for the quasar.
Ancillary program target selection is tracked with the ANCILLARY_TARGET1 and
ANCILLARY_TARGET2 flag bits. The bit values and the corresponding program
names are listed in Dawson et al. (2013, AJ, 145, 10), Alam et al. (2015,
ApJS, 219, 12), and Appendix B of the reference paper. The SEQUELS program
targeted different classes of objects (quasars, luminous red galaxies or
LRGs, galaxy clusters). All the SEQUELS targets are identified by the
ANCILLARY_TARGET2 bit 53, and the details of each target class is provided
through the eboss_ts_flag (EBOSS_TARGET0) flag (see Table A.1 of the
reference paper).
Eboss_TS_Flag
The target selection flag for the SDSS-IV/eBOSS pilot survey, EBOSS_TARGET0.
The SEQUELS program targeted different classes of objects (quasars, luminous
red galaxies or LRGs, galaxy clusters). All the SEQUELS targets are
identified by the ANCILLARY_TARGET2 bit 53, and the details of each target
class is provided through this flag (see Table A.1 of the reference paper).
Number_Boss_Spectra
The number of additional spectra of the quasar that are available in
SDSS-III/BOSS. If a quasar in DR12Q was observed more than once during the
survey, the number of additional SDSS-III/BOSS spectra is given by this
parameter. If a quasar was observed N times in total, the best spectrum is
identified (and is specified in the values of the spect_plate_number,
spect_date, and spect_fiber_number parameters), and the value of number_boss
spectra will be N-1. The details of these up to 32 additional spectra
(spect_plate_number, spect_date, spect_fiber_number and their overall
signal-to-noise ratios) are available in the CDS version of this table at
http://cdsarc.u-strasbg.fr/ftp/cats/VII/279/dr12q.dat.gz.
SDSS_Dr7_Quasar_Flag
A quasar previously known from the SDSS-DR7 quasar catalog (Schneider et al.
2010, AJ, 139, 2360, CDS Cat. VII/260) has a value equal to 1 for this
parameter, and is set to 0 otherwise. During Year 1 and 2, all SDSS-DR7
quasars with z >= 2.15 were re-observed. After Year 2, all SDSS-DR7 quasars
with z >= 1.8 have been systematically re-observed.
SDSS_Dr7_Plate_Number
The SDSS-DR7 spectroscopic plate number for the quasar.
SDSS_Dr7_Spect_Date
The date when the SDSS-DR7 spectroscopic data were obtained.
SDSS_Dr7_Fiber_Number
The SDSS-DR7 spectroscopic fiber number for the quasar.
Uniform_Sample_Flag
The "uniform" sample flag value for the quasar. The authors provide a uniform
flag in order to identify a homogeneously selected sample of quasars.
Although the CORE sample has been designed to have a well understood,
uniform, and reproducible selection function, its definition varied over the
first year of the survey. Thus, the nominal CORE quasars are not a
uniformly-selected sample. Areas within which all the algorithms used in the
quasar target selection are uniform are called "Chunks". The definition of
each of them can be found in Ross et al. (2012, ApJS, 199, 3). After Chunk
12, CORE targets were selected with the XDQSO technique alone (Bovy et al.
2011, ApJ, 729, 141). These objects have uniform = 1. Quasars in this catalog
with uniform = 2 are objects that would have been selected by XDQSO if it had
been the CORE algorithm prior to Chunk 12. Objects with uniform = 2 are
reasonably complete to what XDQSO would have selected, even prior to Chunk
12. But, as DR12Q only contains information about spectroscopically confirmed
quasars, not about all targets, care must be taken to create a statistical
sample from the uniform flag. See, e.g., the discussion regarding the
creation of a statistical sample for clustering measurements in White et al.
(2012, MNRAS, 424, 933) and Eftekharzadeh et al. (2015, MNRAS, 452, 2779).
Quasars with uniform = 0 are not homogeneously selected CORE targets.
Spectral_Index
The spectral index of the quasar's continuum, alpha, in the SDSS spectrum.
The continuum is approximated by a power-law, fcont ~ nualpha, and is
computed in emission line free regions: 1450 - 1500 A, 1700 - 1850 A and 1950
- 2750 A in the quasar rest frame.
SNR_Overall
The median signal-to-noise ratio (SNR) per pixel for the quasar, computed
over the whole spectrum for this "best" spectrum. (When an object was
observed more than once, the authors selected the best quality spectrum as
defined by the SDSS pipeline, i.e. with SPECPRIMARY = 1).
SNR_1700_Angstrom
The median SNR per pixel for the quasar, computed over the window 1650 - 1750
A, in the quasar rest frame. If the wavelength range is not covered by the
BOSS spectrum, the value is set to null (-1 in the original table).
SNR_3000_Angstrom
The median SNR per pixel for the quasar, computed over the window 2950 - 3050
A, in the quasar rest frame. If the wavelength range is not covered by the
BOSS spectrum, the value is set to null (-1 in the original table).
SNR_5150_Angstrom
The median SNR per pixel for the quasar, computed over the window 5100 - 5250
A, in the quasar rest frame. If the wavelength range is not covered by the
BOSS spectrum, the value is set to null (-1 in the original table).
C_IV_FWHM
The FWHM (in km s-1) of the C IV emission line. If the emission line is not
in the spectrum, the FWHM is set to null (-1 in the original table).
C_IV_Blue_Hwhm
The blue half width at half-maximum (HWHM, in km s-1: the sum of the blue
and red HWHMs equals the FWHM) of the C IV emission line. If the emission
line is not in the spectrum, the blue HWHM is set to null (-1 in the original
table).
C_IV_Red_Hwhm
The red half width at half-maximum (HWHM, in km s-1: the sum of the blue
and red HWHMs equals the FWHM) of the C IV emission line. If the emission
line is not in the spectrum, the blue HWHM is set to null (-1 in the original
table).
C_IV_Amplitude
The amplitude of the C IV emission line in units of the median rms pixel
noise (see Section 4 of Paris et al. 2012, A&A, 548, A66).
C_IV_RF_EW
The rest frame equivalent width in Angstrom of the C IV emission line. If the
emission line is not in the spectrum, this quantity is set to null (-1 in the
original table).
C_IV_RF_Ew_Error
The uncertainty in the rest frame equivalent width in Angstrom of the C IV
emission line. If the emission line is not in the spectrum, this quantity is
set to null (-1 in the original table).
C_III_FWHM
The FWHM in km s-1 of the C III] emission line complex. If the emission line
is not in the spectrum, this quantity is set to null (-1 in the original
table). It is well known that C III] 1909A is blended with Si III 1892A and to
a lesser extent with Al III 1857A. The authors do not attempt to deblend
these lines. Therefore the redshift and red HWHM derived for this blend
correspond to C III] 1909A. The blue HWHM is obviously affected by the blend.
C_III_Blue_Hwhm
The blue HWHM in km s-1 of the C III] emission line complex. If the emission
line is not in the spectrum, this quantity is set to null (-1 in the original
table). It is well known that C III] 1909A is blended with Si III 1892A and to
a lesser extent with Al III 1857A. The authors do not attempt to deblend
these lines. Therefore the redshift and red HWHM derived for this blend
correspond to C III] 1909A. The blue HWHM is obviously affected by the blend.
C_III_Red_Hwhm
The red HWHM in km s-1 of the C III] emission line complex. If the emission
line is not in the spectrum, this quantity is set to null (-1 in the original
table). It is well known that C III] 1909A is blended with Si III 1892A and to
a lesser extent with Al III 1857A. The authors do not attempt to deblend
these lines. Therefore the redshift and red HWHM derived for this blend
correspond to C III] 1909A. The blue HWHM is obviously affected by the blend.
C_III_Amplitude
The amplitude of the C III emission line complex in units of the median rms
pixel noise (see Section 4 of Paris et al. 2012, A&A, 548, A66).
C_III_RF_EW
The rest frame equivalent width in Angstrom of the C III emission line
complex. If the emission line is not in the spectrum, this quantity is set to
null (-1 in the original table).
C_III_RF_Ew_Error
The uncertainty in the rest frame equivalent width in Angstrom of the C III
emission line complex. If the emission line is not in the spectrum, this
quantity is set to null (-1 in the original table).
Mg_II_FWHM
The FWHM in km s-1 of the Mg II emission line. If the emission line is not
in the spectrum, this quantity is set to null (-1 in the original table).
Mg_II_Blue_Hwhm
The blue HWHM in km s-1 of the Mg II emission line. If the emission line is
not in the spectrum, this quantity is set to null (-1 in the original table).
Mg_II_Red_Hwhm
The red HWHM in km s-1 of the Mg II emission line. If the emission line is
not in the spectrum, this quantity is set to null (-1 in the original table).
Mg_II_Amplitude
The amplitude of the Mg II emission line in units of the median rms pixel
noise (see Section 4 of Paris et al. 2012, A&A, 548, A66).
Mg_II_RF_EW
The rest frame equivalent width in Angstrom of the Mg II emission line. If
the emission line is not in the spectrum, this quantity is set to null (-1 in
the original table). The authors do not correct for the neighboring Fe II
emission.
Mg_II_RF_Ew_Error
The uncertainty in the rest frame equivalent width in Angstrom of the Mg II
emission line. If the emission line is not in the spectrum, this quantity is
set to null (-1 in the original table).
Bal_Vi_Flag
The BAL flag from the visual inspection, BAL_FLAG_VI. If a BAL feature was
identified in the course of the visual inspection, BAL_FLAG_VI is set to 1, 0
otherwise. Note that BAL quasars are flagged during the visual inspection at
any redshift and whenever a BAL feature is seen in the spectrum (not only for
C IV absorption troughs)..
C_IV_Trough_BI
The balnicity index (BI; Weymann et al. 1991, ApJ, 373, 23) for C IV troughs,
expressed in km s-1. See the definition in Section 4.6 of
the reference paper. The Balnicity index is measured for
quasars with z > 1.57 only, so that the trough enters into the BOSS wavelength
region. If the BAL flag from the visual inspection is set to 1 and the BI is
equal to 0, this means either that there is no C IV trough (but a trough is
seen in another transition) or that the trough seen during the visual
inspection does not meet the formal requirement of the BAL definition. In
cases with bad fits to the continuum, the balnicity index and its error are
set to null (-1 in the original table).
C_IV_Trough_Bi_Error
The error in the BI parameter of the C IV trough, in km s-1.
C_IV_Trough_Ai
The absorption index AI for the C IV troughs expressed in km s-1. See the
definition in Section 4.6 of the reference paper. In cases with bad continuum
fits, the absorption index and its error are set to null (-1 in the original
table).
C_IV_Trough_Ai_Error
The error in the AI parameter of the C IV trough, in km s-1.
C_IV_Trough_Chi2
Following Trump et al. (2006, ApJS, 165, 1), the authors calculate the
reduced chi-squared which they call Chi2trough for each C IV trough from
Equation (3) of the reference paper. They require that troughs have
Chi2trough > 10 to be considered as true troughs.
C_IV_Troughs_2k_Num
The number of distinct C IV troughs of width larger than 2,000 km/s.
C_IV_Troughs_2k_Min_Vel
The minimum velocity limit of the velocity range in which C IV troughs of
width larger than 2000 km s-1 and reaching at least 10% below the continuum
are to be found. Velocities are positive bluewards and the zero of the scale
is at the visual inspection redshift, Z_VI. So, if there are multiple
troughs, this value demarcates the range from the first to the last trough.
C_IV_Troughs_2k_Max_Vel
The maximum velocity limit of the velocity range in which C IV troughs of
width larger than 2000 km s-1 and reaching at least 10% below the continuum
are to be found. Velocities are positive bluewards and the zero of the scale
is at the visual inspection redshift, Z_VI. So, if there are multiple
troughs, this value demarcates the range from the first to the last trough.
C_IV_Troughs_450_Num
The number of distinct C IV troughs of width larger than 450 km/s.
C_IV_Troughs_450_Min_Vel
The minimum velocity limit of the velocity range in which C IV troughs of
width larger than 450 km s-1 and reaching at least 10% below the continuum
are to be found. Velocities are positive bluewards and the zero of the scale
is at the visual inspection redshift, Z_VI. So, if there are multiple
troughs, this value demarcates the range from the first to the last trough.
C_IV_Troughs_450_Max_Vel
The maximum velocity limit of the velocity range in which C IV troughs of
width larger than 450 km s-1 and reaching at least 10% below the continuum
are to be found. Velocities are positive bluewards and the zero of the scale
is at the visual inspection redshift, Z_VI. So, if there are multiple
troughs, this value demarcates the range from the first to the last trough.
Si_IV_Trough_RF_EW
The rest frame equivalent width in A of Si IV troughs detected in BAL quasars
with BI of C IV > 500 km s-1 and SNR_1700 > 5. They are set to 0 otherwise
or in cases where no trough is detected and to -1 if the continuum is not
reliable.
C_IV_Trough_RF_EW
The rest frame equivalent width in A of C IV troughs detected in BAL quasars
with BI of C IV > 500 km s-1 and SNR_1700 > 5. They are set to 0 otherwise
or in cases where no trough is detected and to -1 if the continuum is not
reliable.
Al_III_Trough_RF_EW
The rest frame equivalent width in A of Al III troughs detected in BAL
quasars with BI of C IV > 500 km s-1 and SNR_1700 > 5. They are set to 0
otherwise or in cases where no trough is detected and to -1 if the continuum
is not reliable.
Imaging_Run_Number
The SDSS Imaging Run number of the photometric observation used in the
catalog.
Imaging_Date
The date of the SDSS photometric observation used in the catalog.
Phot_Proc_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 SDSS camera column number containing the image of the object (see
Stoughton et al. 2002, AJ, 123, 485 for a description of this parameter).
Field_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 (see Stoughton et al. 2002, AJ, 123,
485 for a description of this parameter).
Flux_U_Band
The SDSS-DR12 PSF flux of the quasar in the u band in nanomaggies (see
Overview for definition) and not corrected for Galactic extinction.
Flux_G_Band
The SDSS-DR12 PSF flux of the quasar in the g band in nanomaggies (see
Overview for definition) and not corrected for Galactic extinction.
Flux_R_Band
The SDSS-DR12 PSF flux of the quasar in the r band in nanomaggies (see
Overview for definition) and not corrected for Galactic extinction.
Flux_I_Band
The SDSS-DR12 PSF flux of the quasar in the i band in nanomaggies (see
Overview for definition) and not corrected for Galactic extinction.
Flux_Z_Band
The SDSS-DR12 PSF flux of the quasar in the z band in nanomaggies (see
Overview for definition) and not corrected for Galactic extinction.
Flux_U_Band_IV
The inverse variance of the SDSS-DR12 PSF flux in the u band in nanomaggies
(see Overview for definition) and not corrected for Galactic extinction.
Flux_G_Band_IV
The inverse variance of the SDSS-DR12 PSF flux in the g band in nanomaggies
(see Overview for definition) and not corrected for Galactic extinction.
Flux_R_Band_IV
The inverse variance of the SDSS-DR12 PSF flux in the r band in nanomaggies
(see Overview for definition) and not corrected for Galactic extinction.
Flux_I_Band_IV
The inverse variance of the SDSS-DR12 PSF flux in the i band in nanomaggies
(see Overview for definition) and not corrected for Galactic extinction.
Flux_Z_Band_IV
The inverse variance of the SDSS-DR12 PSF flux in the z band in nanomaggies
(see Overview for definition) and not corrected for Galactic extinction.
Umag
The SDSS-DR12 PSF AB magnitude of the quasar in the u band (Lupton et al.
1999, AJ, 118, 1406) and not corrected for Galactic extinction.
Umag_Error
The error in the SDSS-DR12 PSF AB magnitude in the u band.
Gmag
The SDSS-DR12 PSF AB magnitude of the quasar in the g band (Lupton et al.
1999, AJ, 118, 1406) and not corrected for Galactic extinction.
This magnitude is an Asinh magnitude as defined in Lupton et al. (1999).
Gmag_Error
The error in the SDSS-DR12 PSF AB magnitude in the g band.
Rmag
The SDSS-DR12 PSF AB magnitude of the quasar in the r band (Lupton et al.
1999, AJ, 118, 1406) and not corrected for Galactic extinction.
This magnitude is an Asinh magnitude as defined in Lupton et al. (1999).
Rmag_Error
The error in the SDSS-DR12 PSF AB magnitude in the r band.
Imag
The SDSS-DR12 PSF AB magnitude of the quasar in the i band (Lupton et al.
1999, AJ, 118, 1406) and not corrected for Galactic extinction
This magnitude is an Asinh magnitude as defined in Lupton et al. (1999).
Imag_Error
The error in the SDSS-DR12 PSF AB magnitude in the i band.
Zmag
The SDSS-DR12 PSF AB magnitude of the quasar in the z band (Lupton et al.
1999, AJ, 118, 1406) and not corrected for Galactic extinction.
This magnitude is an Asinh magnitude as defined in Lupton et al. (1999).
Zmag_Error
The error in the SDSS-DR12 PSF AB magnitude in the z band.
Target_Flux_U_Band
The DR8 PSF flux of the quasar (not corrected for Galactic extinction),
expressed in nanomaggies, in the u band. This photometry is the one that was
used for the main quasar target selection (Ross et al. 2012, ApJS, 199, 3).
Target_Flux_G_Band
The DR8 PSF flux of the quasar (not corrected for Galactic extinction),
expressed in nanomaggies, in the g band. This photometry is the one that was
used for the main quasar target selection (Ross et al. 2012, ApJS, 199, 3).
Target_Flux_R_Band
The DR8 PSF flux of the quasar (not corrected for Galactic extinction),
expressed in nanomaggies, in the r band. This photometry is the one that was
used for the main quasar target selection (Ross et al. 2012, ApJS, 199, 3).
Target_Flux_I_Band
The DR8 PSF flux of the quasar (not corrected for Galactic extinction),
expressed in nanomaggies, in the i band. This photometry is the one that was
used for the main quasar target selection (Ross et al. 2012, ApJS, 199, 3).
Target_Flux_Z_Band
The DR8 PSF flux of the quasar (not corrected for Galactic extinction),
expressed in nanomaggies, in the z band. This photometry is the one that was
used for the main quasar target selection (Ross et al. 2012, ApJS, 199, 3).
Abs_Imag
The absolute magnitude of the quasar in the i band at z = 2 calculated after
correction for Galactic extinction and assuming H0 = 70 km s-1 Mpc-1,
OmegaM = 0.3, OmegaLambda = 0.7, and a power-law (frequency) continuum
index of -0.5. The K-correction is computed using Table 4 from Richards et
al. (2006, AJ, 131, 2766). The authors use the SDSS primary photometry to
compute this value.
GI_Color_Offset
The Delta(g-i) color of the quasar, which is the difference in the Galactic
extinction (g-i) corrected 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 column will contain a null.
Gal_Ext_U_Band
The Galactic extinction towards the quasar in the u band based on the maps of
Schlegel et al. (1998, ApJ, 500, 525). The quasar target selection was done
using these maps.
Gal_Ext_G_Band
The Galactic extinction towards the quasar in the g band based on the maps of
Schlegel et al. (1998, ApJ, 500, 525). The quasar target selection was done
using these maps.
Gal_Ext_R_Band
The Galactic extinction towards the quasar in the r band based on the maps of
Schlegel et al. (1998, ApJ, 500, 525). The quasar target selection was done
using these maps.
Gal_Ext_I_Band
The Galactic extinction towards the quasar in the i band based on the maps of
Schlegel et al. (1998, ApJ, 500, 525). The quasar target selection was done
using these maps.
Gal_Ext_Z_Band
The Galactic extinction towards the quasar in the z band based on the maps of
Schlegel et al. (1998, ApJ, 500, 525). The quasar target selection was done
using these maps.
SF_Gal_Ext_U_Band
The Galactic extinction towards the quasar in the u band based on the maps of
Schlafly and Finkbeiner (2011, ApJ, 737, 103).
SF_Gal_Ext_G_Band
The Galactic extinction towards the quasar in the g band based on the maps of
Schlafly and Finkbeiner (2011, ApJ, 737, 103).
SF_Gal_Ext_R_Band
The Galactic extinction towards the quasar in the r band based on the maps of
Schlafly and Finkbeiner (2011, ApJ, 737, 103).
SF_Gal_Ext_I_Band
The Galactic extinction towards the quasar in the i band based on the maps of
Schlafly and Finkbeiner (2011, ApJ, 737, 103).
SF_Gal_Ext_Z_Band
The Galactic extinction towards the quasar in the z band based on the maps of
Schlafly and Finkbeiner (2011, ApJ, 737, 103).
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 expected to be typically less than ~ 1 x 1020
cm-2 (e.g., see Section 5 of Elvis et al. 1994, ApJS, 95, 413).
Var_Flag
A flag (VAR_MATCHED) for variability information about the quasar. If no such
information is available, VAR_MATCHED is set to 0. When enough photometric
epochs are available to build a lightcurve, VAR_MATCHED is equal to the
number of photometric epochs used. For PTF-selected objects (the
eboss_ts_flag parameter EBOSS_TARGET0, bit 11), both PTF and SDSS photometry
were used. For objects lying in the stripe 82 region, only SDSS photometry
was used.
Var_Chi2
The quasar light curve was fit assuming a constant flux (see Sect. 2.3 in
Palanque-Delabrouille et al. 2011, A&A, 530, A122). This parameter is the
reduced chi2 of this fit, VAR_CHI2.
Var_Sfpar_A
The best-fit value of the structure function parameter, A, characterizing the
variability of the source, as defined in equation (5) and Section 4.8 of the
reference paper.
Var_Sfpar_Gamma
The best-fit value of the structure function parameter, Gamma, characterizing
the variability of the source, as defined in equation (5) and Section 4.8 of
the reference paper.
RASS_Log_Count_Rate
The logarithm of the vignetting-corrected count rate (photons s-1) in the
broad energy band (0.1 - 2.4 keV) from the ROSAT All-Sky Survey (RASS) Faint
Source Catalog (Voges et al. 2000, IAUC 7432) and the RASS Bright Source
Catalog (Voges et al. 1999, A&A, 349, 389). The matching radius was set to 30
arcsecond (see Sect. 4.7.6 of the reference paper).
RASS_SNR
The signal-to-noise ratio of the RASS measurement.
SDSS_RASS_Offset
The angular separation between the SDSS-DR12 and the ROSAT All-Sky Survey
locations of the quasar (in arcseconds).
Number_XMM_Detections
The number of XMM-Newton matches in a 5-arcsecond radius around the SDSS-DR12
quasar position.
XMM_Best_FB_Flux
The total X-ray flux (0.2-12 keV) from the three XMM-Newton CCDs (MOS1, MOS2
and PN), of the XMM-Newton source matched to the SDSS source,
in erg cm-2 s-1. In the case of multiple XMM-Newton observations, only the
longest exposure was used to compute the reported X-ray flux.
XMM_Best_FB_Flux_Error
The error in the total X-ray flux (0.2-12 keV) from the XMM-Newton matching to
the SDSS source, in erg cm-2 s-1
XMM_Best_SB_Flux
The soft X-ray flux (0.2-2 keV) from the XMM-Newton matching to the SDSS
source, in erg cm-2 s-1. In the case of multiple XMM-Newton observations,
the values reported here are the weighted average of all the XMM-Newton
detections in this band.
XMM_Best_SB_Flux_Error
The error in the soft X-ray flux (0.2-2 keV) from the
XMM-Newton matching to the SDSS source, in erg cm-2 s-1.
XMM_Best_HB_Flux
The hard X-ray flux (4.5-12 keV) from the XMM-Newton matching to the SDSS
source, in erg cm-2 s-1. In the case of multiple XMM-Newton observations,
the values reported here are the weighted average of all the XMM-Newton
detections in this band..
XMM_Best_HB_Flux_Error
The error in the hard X-ray flux (4.5-12 keV) from the XMM-Newton matching to
the SDSS source, in erg cm-2 s-1.
XMM_Mean_FB_Flux
The total X-ray flux (0.2-12 keV) from the XMM-Newton matching to the SDSS
source, expressed in erg cm-2 s-1. In the case of multiple observations,
the values reported here are the weighted average of all the XMM-Newton
detections in this band.
XMM_Mean_FB_Flux_Error
The error in the total mean X-ray flux (0.2-12 keV) from the
XMM-Newton matching to the SDSS source, expressed in erg cm-2 s-1.
XMM_Best_FB_Lx
The total (0.2-12 keV) X-ray luminosity derived from the flux computed in
xmm_best_fb_flux, expressed in erg s-1. This value is computed using the
visual inspection redshift (Z_VI) and the cosmological model described in the
Overview above, and is not absorption corrected.
XMM_Best_SB_Lx
The soft (0.2-2 keV) X-ray luminosity derived from the flux computed in
xmm_best_sb_flux, expressed in erg s-1. This value is computed using the
visual inspection redshift (Z_VI) and the cosmological model described in the
Overview above, and is not absorption corrected.
XMM_Best_HB_Lx
The hard (4.5-12 keV) X-ray luminosity derived from the flux computed in
xmm_best_hb_flux, expressed in erg s-1. This value is computed using the
visual inspection redshift (Z_VI) and the cosmological model described in the
Overview above, and is not absorption corrected.
XMM_Mean_FB_Lx
The total (0.2-12 keV) X-ray luminosity derived from the flux computed in
xmm_mean_fb_flux, expressed in erg s-1. This value is computed using the
visual inspection redshift (Z_VI) and the cosmological model described in the
Overview above, and is not absorption corrected.
XMM_Best_HB_Flux_Flag
In the case of an unreliable detection or no detection in the hard
band, the flux reported in the xmm_best_hb_flux parameter is an upper limit.
In that case, this flag parameter value is set to -1.
SDSS_XMM_Offset
The angular separation between the SDSS-DR12 and the XMM-Newton locations of
the quasar (in arcseconds).
GALEX_Match_Flag
This flag parameter (GALEX_MATCHED) is set to 1 if the SDSS-DR12 quasar has a
matched with a GALEX source, else is set to 0.
GALEX_FUV_Flux
The flux of the GALEX counterpart, aperture-photometered from the original
GALEX images, in the FUV band. The fluxes are expressed in nanomaggies.
GALEX_FUV_Flux_IV
The inverse variance of the GALEX FUV flux (in nanomaggies-2).
GALEX_NUV_Flux
The flux of the GALEX counterpart, aperture-photometered from the original
GALEX images, in the NUV band. The fluxes are expressed in nanomaggies.
GALEX_NUV_Flux_IV
The inverse variance of the GALEX NUV flux (in nanomaggies-2).
Jmag
The J magnitude from the Two Micron All Sky Survey All-Sky (2MASS) Data
Release Point Source Catalog (Cutri et al. 2003, CDS Cat. II/246) using a
matching radius of 2.0 arcseconds (see Section 4.7.3 of the reference paper).
A non-detection by 2MASS is indicated by a null value (0.000 in the original
table). Note that the 2MASS measurements are Vega-based, not AB, magnitudes.
Jmag_Error
The error in the 2MASS J magnitude.
Jmag_SNR
The signal-to-noise ratio of the 2MASS J-band measurement.
Jmag_Flag
The 2MASS jrd flag that gives the meaning of peculiar values of the
corresponding band magnitude and its error (see
http://www.ipac.caltech.edu/2mass/releases/allsky/doc/explsup.html).
Hmag
The H magnitude from the Two Micron All Sky Survey All-Sky (2MASS) Data
Release Point Source Catalog (Cutri et al. 2003, CDS Cat. II/246) using a
matching radius of 2.0 arcseconds (see Section 4.7.3 of the reference paper).
A non-detection by 2MASS is indicated by a null value (0.000 in the original
table). Note that the 2MASS measurements are Vega-based, not AB, magnitudes.
Hmag_Error
The error in the 2MASS H magnitude.
Hmag_SNR
The signal-to-noise ratio of the 2MASS H-band measurement.
Hmag_Flag
The 2MASS jrd flag that gives the meaning of peculiar values of the
corresponding band magnitude and its error (see
http://www.ipac.caltech.edu/2mass/releases/allsky/doc/explsup.html).
Kmag
The K magnitude from the Two Micron All Sky Survey All-Sky (2MASS) Data
Release Point Source Catalog (Cutri et al. 2003, CDS Cat. II/246) using a
matching radius of 2.0 arcseconds (see Section 4.7.3 of the reference paper).
A non-detection by 2MASS is indicated by a null value (0.000 in the original
table). Note that the 2MASS measurements are Vega-based, not AB, magnitudes.
Kmag_Error
The error in the 2MASS K magnitude.
Kmag_SNR
The signal-to-noise ratio of the 2MASS K-band measurement.
Kmag_Flag
The 2MASS jrd flag that gives the meaning of peculiar values of the
corresponding band magnitude and its error (see
http://www.ipac.caltech.edu/2mass/releases/allsky/doc/explsup.html).
SDSS_2MASS_Offset
The angular separation between the SDSS and 2MASS positions of the quasar (in
arcseconds).
WISE_W1_Mag
The w1 (3.4 um) magnitude (Vega) of the match to the SDSS-DR12 quasar from
the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010, AJ, 140,
1868) All-Sky Data Release Point Source Catalog using a matching radius of 2
arcseconds.
WISE_W1_Mag_Error
The error in the WISE w1 magnitude of the match to the SDSS-DR12 quasar.
WISE_W1_SNR
The signal-to-noise ratio of the WISE w1-band detection.
WISE_W1_Chi2
The chi-squared of the WISE w1-band detection.
WISE_W2_Mag
The w2 (4.6 um) magnitude (Vega) of the match to the SDSS-DR12 quasar from
the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010, AJ, 140,
1868) All-Sky Data Release Point Source Catalog using a matching radius of 2
arcseconds.
WISE_W2_Mag_Error
The error in the WISE w2 magnitude of the match to the SDSS-DR12 quasar.
WISE_W2_SNR
The signal-to-noise ratio of the WISE w2-band detection.
WISE_W2_Chi2
The chi-squared of the WISE w2-band detection.
WISE_W3_Mag
The w3 (12 um) magnitude (Vega) of the match to the SDSS-DR12 quasar from the
Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010, AJ, 140, 1868)
All-Sky Data Release Point Source Catalog using a matching radius of 2
arcseconds.
WISE_W3_Mag_Error
The error in the WISE w3 magnitude of the match to the SDSS-DR12 quasar.
WISE_W3_SNR
The signal-to-noise ratio of the WISE w3-band detection.
WISE_W3_Chi2
The chi-squared of the WISE w3-band detection.
WISE_W4_Mag
The w4 (22 um) magnitude (Vega) of the match to the SDSS-DR12 quasar from the
Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010, AJ, 140, 1868)
All-Sky Data Release Point Source Catalog using a matching radius of 2
arcseconds.
WISE_W4_Mag_Error
The error in the WISE w4 magnitude of the match to the SDSS-DR12 quasar.
WISE_W4_SNR
The signal-to-noise ratio of the WISE w4-band detection.
WISE_W4_Chi2
The chi-squared of the WISE w4-band detection.
WISE_CC_Flag
The WISE contamination and confusion flag for the source.
WISE_Ph_Flag
The WISE photometric quality flag for the source.
SDSS_Wise_Offset
The angular separation between the SDSS-DR12 and WISE positions of the quasar
(in arcseconds).
UKIDSS_Match_Flag
If an SDSS-DR12 quasar matches UKIDSS aperture-photometric data, this
parameter is set to 1; otherwise, it is set to 0.
UKIDSS_Flux_Y_Band
The Y-band (0.97 - 1.07 um) flux density of the UKIDSS-matched source, in W
m-2 Hz-1. This has been aperture-photometered from the original UKIDSS
images.
UKIDSS_Flux_Y_Band_Error
The error in the Y-band (0.97 - 1.07 um) flux density of the UKIDSS-matched
source, in W m-2 Hz-1.
UKIDSS_Flux_J_Band
The J-band (1.17 - 1.33 um) flux density of the UKIDSS-matched source, in W
m-2 Hz-1. This has been aperture-photometered from the original UKIDSS
images.
UKIDSS_Flux_J_Band_Error
The error in the J-band (1.17 - 1.33 um) flux density of the UKIDSS-matched
source, in W m-2 Hz-1.
UKIDSS_Flux_H_Band
The H-band (1.49 - 1.78 um) flux density of the UKIDSS-matched source, in W
m-2 Hz-1. This has been aperture-photometered from the original UKIDSS
images.
UKIDSS_Flux_H_Band_Error
The error in the H-band (1.49 - 1.78 um) flux density of the UKIDSS-matched
source, in W m-2 Hz-1.
UKIDSS_Flux_K_Band
The K-band (2.03 - 2.37 um) flux density of the UKIDSS-matched source, in W
m-2 Hz-1. This has been aperture-photometered from the original UKIDSS
images.
UKIDSS_Flux_K_Band_Error
The error in the K-band (2.03 - 2.37 um) flux density of the UKIDSS-matched
source, in W m-2 Hz-1.
FIRST_Match_Flag
If there is a source in the FIRST radio catalog (version March 2014) within
2.0 arcseconds of the quasar position, this flag is set to 1, O if not. If
the quasar lies outside of the FIRST footprint, it is set to null (-1 in the
original table).
Flux_20_cm
The FIRST peak flux density of the quasar at 20 cm, in mJy.
SNR_20_cm
The signal-to-noise ratio of the FIRST 20-cm detection of the quasar.
SDSS_FIRST_Offset
The angular separation between the SDSS-DR12 and FIRST positions of the quasar
(in arcseconds).
Contact Person
Questions regarding the SDSSQUASAR database table can be addressed to the HEASARC Help Desk.Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:34:42 EDT
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- Last Modified: 16-Sep-2024