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UVQS - UV-Bright Quasar Survey (UVQS) DR1 Catalog



This table contains data from the first data release (DR1) from the UV-bright Quasar Survey (UVQS) for new z ~ 1 active galactic nuclei (AGN) across the sky. Using simple GALEX UV and WISE near-IR color selection criteria, the authors generated a list of 1,450 primary candidates with FUV < 18.5 mag, that is contained in the HEASARC table (entries with source_sample = 'P'). They obtained discovery spectra, primarily on 3m-class telescopes, for 1,040 of these candidates and confirmed 86% as AGN, with redshifts generally at z > 0.5. Including a small set of observed secondary candidates, the authors report the discovery of 217 AGN with GALEX FUV magnitudes < 18 mag that previously had no reported spectroscopic redshifts. These are excellent potential targets for UV spectroscopy before the end of the Hubble Space Telescope mission. The main data products of UVQS are publicly available through the Mikulski Archive for Space Telescopes (MAST).

The authors have performed an all-sky survey for z ~ 1, FUV-bright quasars selected from GALEX and WISE photometry. In several of the observing runs, conditions were unexpectedly favorable and we exhausted the primary candidates at certain right ascension ranges. To fill the remaining observing time, they generated a secondary candidate list. This secondary set of 2,010 candidates is also contained in this HEASARC table (entries with source_sample = 'S').

The authors proceeded to obtain discovery-quality long-slit spectra (i.e., low-dispersion, large-wavelength coverage, modest signal-to-noise ratio (S/N) of their UV-bright Quasar Survey (UVQS) candidates in one calendar year. The principal facilities were: (i) the dual Kast spectrometer on the 3m Shane telescope at the Lick Observatory; (ii) the Boller & Chivens (BCS) spectrometer on the Irenee du Pont 100-inch telescope at the Las Campanas Observatory; and (iii) the Calar Alto Faint Object Spectrograph on the CAHA 2.2-meter telescope at the Calar Alto Observatory (CAHA). They acquired an additional ~20 spectra on larger aperture telescopes (Keck/ESI, MMT/MBC, Magellan/MagE) during twilight or under poor observing conditions. Typical exposure times were limited to < ~200s, with adjustments for fainter sources or sub-optimal observing conditions. Table 3 in the reference paper provides a list of the details of the observations of these candidates. From the total candidates list of 3,460 objects, the authors measured high-quality redshifts (redshift quality flag values of 3 or greater) for 1,121 sources. They assumed that every source with a recessional velocity vr = z * c < 500 km s-1 was "Galactic", which they associate with the Galaxy and members of the Local Group. This included sources where the eigenspectra fits were poor yet a low vr was indisputable (e.g., stars). Many of these were assigned z = 0 exactly. The remainder of the UVQS sources were assumed to be extragalactic AGN, and the derived redshift information for these sources (which was given in Table 4 of the reference paper) has been incorporated into this HEASARC representation of UVQS. Finally, there were 93 sources with good-quality spectra for which we cannot the authors could not recover a secure redshift. The majority of these have been previously cataloged as blazars (or BL Lac objects). Table 6 in the reference paper lists the sample of these unknown or insecure redshift objects.

Catalog Bibcode



The UV-bright quasar survey (UVQS): DR1.
    Monroe T.R., Xavier Prochaska J., Tejos N., Worseck G., Hennawi J.F.,
    Schmidt T., Tumlinson J., Shen Y.
   <Astron. J., 152, 25-25 (2016)>
   =2016AJ....152...25M    (SIMBAD/NED BibCode)


This table was created by the HEASARC in April 2017 based upon the CDS Catalog J/AJ/152/25 files table1.dat, table2.dat, and table4.dat.


This HEASARC-created flag parameter is set to 'P' to indicate that a source was taken from the list of UVQS primary candidates (Table 1 in the reference paper) or to 'S' to indicate that it was taken from the list of UVQS secondary candidates (Table 2 in the reference paper).

The J2000.0 position-based UVQS quasar candidate designation, viz., 'UVQS', as given in Tables 1 and 2 of the reference paper. The names given in Tables 1 and 2 are in general consistent with their J2000.0 positions. When ingesting this table the HEASARC discovered that the names in Table 4 of the reference paper which contained the redshift information were often slightly different than those in Tables 1 and 2, the lists of primary and secondary candidates, respectively. The differences were usually minor, e.g., a difference of 1 in the last digit of the RA or Dec parts of the name, but in some cases they were larger. The most egregious examples of the latter are the following:

            Table 4 name            Table 1 or 2 name

     UVQS J101124.51-044215.5 ~> UVQS J101124.47-044216.4
     UVQS J104844.14+260312.8 ~> UVQS J104844.19+260312.2
     UVQS J110948.50-083014.7 ~> UVQS J110948.49-083015.0
     UVQS J120443.37+311038.2 ~> UVQS J120443.33+311038.2
     UVQS J121628.70-070912.4 ~> UVQS J121628.65-070913.0
     UVQS J153153.82+621042.6 ~> UVQS J153153.81+621042.3
     UVQS J154943.37+211403.8 ~> UVQS J154943.33+211403.4
     UVQS J171555.62+360644.0 ~> UVQS J171555.58+360644.1
     UVQS J173003.89+330104.6 ~> UVQS J173003.86+330104.9
     UVQS J173114.58+323248.7 ~> UVQS J173114.53+323248.6
     UVQS J174227.91+373337.4 ~> UVQS J174227.85+373337.9
     UVQS J180650.80+694928.4 ~> UVQS J180650.68+694928.1
     UVQS J181226.80+540108.1 ~> UVQS J181226.76+540108.5
To create this representation of the UVQS DR1 catalog, the HEASARC matched entries in Table 4 with those in Tables 1 and 2 using a "fuzzy matching" technique.

The Right Ascension of the UVQS DR1 AGN candidate in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 10-5 degrees in the original table.

The Declination of the UVQS DR1 AGN candidate in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 10-5 degrees in the original table.

The Galactic Longitude of the UVQS DR1 AGN candidate.

The Galactic Latitude of the UVQS DR1 AGN candidate.

The WISE W1-band (3.4-micron) magnitude of the UVQS DR1 AGN candidate.

The WISE W2-band (4.6-micron) magnitude of the UVQS DR1 AGN candidate.

The GALEX FUV-band (1344-1786 Angstrom) magnitude of the UVQS DR1 AGN candidate.

The GALEX NUV-band (1771-2831 Angstrom) magnitude of the UVQS DR1 AGN candidate.

The spectroscopic redshift of the UVQS DR1 AGN candidate.

The 1-sigma uncertainty in the spectroscopic redshift of the UVQS DR1 AGN candidate. The redshift uncertainty was derived from a template fit to the spectrum. The authors report a minimum redshift error of 0.003 from systematic uncertainties in their fitting procedure.

A quality flag which indicates the quality code for the spectroscopic redshift of the UVQS DR1 AGN candidate. The quality code scheme is defined as below:

        0 = Poor or unusable;
        3 = Confident;
        5 = Excellent.
These flag values are a good proxy for the S/N of the spectrum from which the redshift was obtained. Note that even spectra without spectral features may have high values for this quality flag parameter.

A flag parameter which indicates whether ('Y') or not ('N') the source is a new AGN candidate, specifically if its position is greater than 10 arcseconds offset from any quasar in the Million Quasar (MILLIQUAS) catalog (v4.5; see Flesch 2015, CDS Cat. VII/273) that has a published spectroscopic redshift.

Contact Person

Questions regarding the UVQS database table can be addressed to the HEASARC Help Desk.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 23-Nov-2022 19:37:48 EST