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VLA 6-GHz Observations of Low-Redshift SDSS QSOs
This table contains results from 6-GHz Jansky Very Large Array (JVLA) observations covering a volume-limited sample of 178 low-redshift (0.2 < z <0.3) optically selected quasi-stellar objects (QSOs). These 176 radio detections fall into two clear categories: (1) about 20% are radio-loud QSOs (RLQs) with spectral luminosities of L<sub>6</sub> >~ 10<sup>23.2</sup> W/Hz that are primarily generated in the active galactic nucleus (AGN) responsible for the excess optical luminosity that defines a bona fide QSO; and (2) the remaining 80% that are radio-quiet QSOs (RQQs) that have 10<sup>21</sup> <~ L<sub>6</sub> <~ 10<sup>23.2</sup> W/Hz and radio sizes <~ 10 kpc, and the authors suggest that the bulk of their radio emission is powered by star formation in their host galaxies. "Radio-silent" QSOs (L_6_<~ 10<sup>21</sup> W/Hz) are rare, so most RQQ host galaxies form stars faster than the Milky Way; they are not "red and dead" ellipticals. Earlier radio observations did not have the luminosity sensitivity of L<sub>6</sub> <~ 10<sup>21</sup> W/Hz that is needed to distinguish between such RLQs and RQQs. Strong, generally double-sided radio emission spanning >> 10 kpc was found to be associated with 13 of the 18 RLQ cores with peak flux densities of S<sub>p</sub> > 5 mJy/beam (log(L) >~ 24). The radio luminosity function of optically selected QSOs and the extended radio emission associated with RLQs are both inconsistent with simple "unified" models that invoke relativistic beaming from randomly oriented QSOs to explain the difference between RLQs and RQQs. Some intrinsic property of the AGN or their host galaxies must also determine whether or not a QSO appears radio-loud. The authors have reprocessed the VLA observations of a sample of SDSS QSOs discussed in Kimball et al. (2011, ApJ, 739, L29). These were obtained using the VLA C configuration with a central frequency of 6 GHz and a bandwidth of 2 GHz in each of the two circular polarizations: with natural weighting the synthesized beam width was 3.5 arcseconds FWHM. The authors generated a catalog of radio sources associated with each QSO. They detected radio emission at 6 GHz from all but two of the 178 color-selected SDSS QSOs contained in this volume-limited sample of QSOs more luminous than M<sub>i</sub> = -23 and with redshifts 0.2 < z < 0.3. All calculations in the reference paper assume a flat LambdaCDM cosmology with H<sub>0</sub> = 70 km s<sup>-1</sup> Mpc<sup>-1</sup> and Omega<sub>Lambda</sub> = 0.7. Spectral luminosities are specified by their source-frame frequencies, flux densities are specified in the observer's frame, and a mean spectral index of alpha = d(log S)/d(log nu) = -0.7 is used to make frequency conversions This table was created by the HEASARC in April 2017 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/831/168">CDS Catalog J/ApJ/831/168</a> file table1.dat. This is a service provided by NASA HEASARC .
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Optically-Selected QSOS NVSS-Detected Source Catalog
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The authors used the 1.4-GHz NRAO VLA Sky Survey (NVSS) to study radio sources in two color-selected QSO samples: a volume-limited sample of 1,313 QSOs defined by Mi < -23 in the redshift range 0.2 < z < 0.45 and a magnitude-limited sample of 2,471 QSOs with mr <= 18.5 and 1.8 < z < 2.5. About 10% were detected above the 2.4-mJy NVSS catalog limit and are powered primarily by active galactic nuclei (AGNs). The space density, rho, of the low-redshift QSOs evolves as rho ~ (1 + z)6. In both redshift ranges, the flux-density distributions and luminosity functions of QSOs stronger than 2.4 mJy are power laws, with no features to suggest more than one kind of radio source. Extrapolating the power laws to lower luminosities predicts the remaining QSOs should be extremely radio quiet, but they are not. Most were detected statistically on the NVSS images with median peak flux densities Sp of ~ 0.3 mJy/beam and ~ 0.05 mJy/beam in the low- and high-redshift samples, corresponding to spectral luminosities log L1.4GHz ~ 22.7 and ~ 24.1 W/Hz, respectively. The authors suggest that the faint radio sources are powered by star formation at rates dM/dt of ~ 20 M_{sun}_/yr in the moderate luminosity (median Mi of ~ -23.4) low-redshift QSOs and dM/dt ~ 500Msun/yr in the very luminous (median Mi ~ -27.5) high-redshift QSOs. Such luminous starbursts (IR/Lsun)> ~ 11.2 and ~ 12.6, respectively) are consistent with "quasar mode" accretion in which cold gas flows fuel both AGN and starburst. The SDSS DR7 QSO catalog (Schneider et al. 2010, AJ, 139, 2360) is complete to i = 19.1 mag over a solid angle of 2.66 sr around the North Galactic Pole. It contains the small sample of 179 color-selected QSOs defined by Mi < -23 in the narrow redshift range 0.2 < z < 0.3 studied by Kimball et al. (2011, ApJ, 739, L29) and the larger sample of 1,313 QSOs in the wider redshift range 0.2 < z < 0.45 discussed here. Note that these magnitudes were calculated for an H0= 71 km/s/Mpc and OmegaM = 0.27 modern flat LambdaCDM cosmology. The entire SDSS DR7 area is covered by the NVSS, whose source catalog is complete for statistical purposes above a peak flux density Sp ~ 2.4 mJy/beam at 1.4 GHz. In the redshift range 0.2 < z < 0.45 the 45" FWHM (full width between half-maximum points) beam of the NVSS spans 150 - 250 kpc. There are 163 (12%) NVSS detections of the 1,313 QSOs in the redshift range 0.2 < z < 0.45 which are listed in Table 1 of the reference paper. The authors also chose a magnitude-limited sample of all 2,471 color-selected DR7 QSOs brighter than mr = 18.5 in the redshift range 1.8 < z < 2.5. The NVSS detected radio emission stronger than S = 2.4 mJy from only 191 (8%) of them: these are listed in Table 3 of the reference paper. This HEASARC table contains the contents of both samples described above. It thus has 163 + 191 = 354 entries, the sum of Tables 1 and 3 from the reference paper. To select only the entries from Table 1, the user should select entries with redshifts from 0.2 to 0.45. To select only the entries from Table 3, the user should select entries with redshifts > 1.8. This table was created by the HEASARC in January 2015 based on CDS Catalog J/ApJ/768/37 files table1.dat and table3.dat. This is a service provided by NASA HEASARC .
GALEX/SDSS z=0.5-1.5 QSO Candidates Catalog
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A sample of ~60,000 objects from the combined Sloan Digital Sky Survey-Galaxy Evolution Explorer (SDSS-GALEX) database with UV-optical colors that should isolate QSOs in the redshift range 0.5 to 1.5 is discussed. The authors use SDSS spectra of a subsample of ~ 4,500 to remove stellar and galaxy contaminants in the sample to a very high level, based on the 7-band photometry. In their paper, they discuss the distributions of redshift, luminosity, and reddening of the 19,100 QSOs (~96%) that they estimate to be present in their final sample of 19,812 point sources. This latter catalog is available in the present table. This paper is based on archival data from the Galaxy Evolution Explorer (GALEX) which is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034, and on data from the SDSS. This table was created by the HEASARC in March 2011 based on the electronic version of Table 2 from the reference paper which was obtained from the AJ web site. Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
2dF QSO Redshift (2QZ) Survey
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The final catalog of the 2dF QSO Redshift Survey (2QZ) is based on Anglo-Australian Telescope 2dF spectroscopic observations of 44,576 color-selected (u, bJ, r) objects with 18.25 < bJ < 20.85 selected from automated plate measurement scans of UK Schmidt Telescope (UKST) photographic plates. The 2QZ comprises 23,338 quasi-stellar objects (QSOs), 12,292 galactic stars (including 2,071 white dwarfs) and 4,558 compact narrow emission-line galaxies. The authors obtained a reliable spectroscopic identification for 86 per cent of objects observed with 2dF. They also report on the 6dF QSO Redshift Survey (6QZ), based on UKST 6dF observations of 1,564 brighter (16 < bJ < 18.25) sources selected from the same photographic input catalog. In total, the authors identified 322 QSOs spectroscopically in the 6QZ. The completed 2QZ is, by more than a factor of 50, the largest homogeneous QSO catalog ever constructed at these faint limits (bJ < 20.85) and high QSO surface densities (35 QSOs/deg2). As such, it represents an important resource in the study of the Universe at moderate-to-high redshifts. The survey area comprised 30 UKST fields, arranged in two 75 degrees by 5 degrees declination strips, one passing across the South Galactic Gap centered on Dec = -30 degrees (the SGP strip), and the other across the North Galactic Gap centered on Dec = 0 degrees (referred to in the reference paper as the equatorial strip, but also known as the NGP strip. The total survey area is 721.6 deg2, when allowance is made for regions of sky excised around bright stars. Spectroscopic observations of the input catalogue were made with the 2dF instrument at the Anglo-Australian Telescope (AAT; the 2QZ sample) and the 6dF instrument at the UKST (the 6QZ sample). 2dF spectroscopic observations began in January 1997 and were completed in April 2002. Six-degree Field observations were performed over the period 2001 March-2002 September. This online catalog was created by the HEASARC in October 2010 based on the machine-readable table 2qz.dat obtained from the CDS (their catalog VII/241). This is a service provided by NASA HEASARC .
GALEX/SDSS Quasar Catalog
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This table contains the result of an analysis of the broad-band UV and optical properties of z ~< 3.4 quasars matched in the Galaxy Evolution Explorer (GALEX) General Data Release 1 (GR1) and the Sloan Digital Sky Survey (SDSS) Data Release 3 (DR3). Of the 6371 SDSS DR3 quasars covered by 204 GALEX GR1 tiles and listed in this table, 5380 (84%) have near-UV detections, while 3034 (48%) have both near-UV and far-UV detections using a matching radius of 7 arcseconds. Most of the DR3 sample quasars are detected in the near-UV until z ~ 1.7, with the near-UV detection fraction dropping to ~50% by z ~ 2. Statistical tests performed on the distributions of non-detections indicate that the optically selected quasars missed in the UV tend to be optically faint or at high redshift. The GALEX positions are shown to be consistent with the SDSS astrometry to within an rms scatter of 0.6 - 0.7 arcsecs in each coordinate, and the empirically determined photometric errors from multi-epoch GALEX observations significantly exceed the Poissonian errors quoted in the GR1 object catalogs. The UV-detected quasars are well separated from stars in UV-optical color-color space, with the UV-optical relative colors suggesting a marginally detected population of reddened objects due to absorption along the line of sight or dust associated with the quasar. The resulting spectral energy distributions (SEDs) cover ~350 - 9000 Angstroms (rest frame), where the overall median SED peaks near the Lyman-Alpha emission line, as found in other UV quasar studies. The large sample size allows the authors to construct median SEDs in small bins of redshift and luminosity, and they find that the median SED becomes harder (bluer) at UV wavelengths for quasars with lower continuum luminosity. The detected UV-optical flux as a function of redshift is qualitatively consistent with attenuation by intervening Lyman-absorbing clouds. This table was created by the HEASARC in October 2009 based on the electronic version of Table 2 from the reference paper which was obtained from the CDS (their catalog J/AJ/133/1780 file table2.dat). This is a service provided by NASA HEASARC .
VLA-COSMOS 3-GHz Large Project Multiwavelength Counterparts Catalog
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In the reference paper, the authors study the composition of the faint radio population selected from the VLA-COSMOS 3-GHz Large Project, a radio continuum survey performed at 10-cm wavelength. The survey covers a 2.6 square degree area with a mean rms of ~2.3 µJy/beam (µJy/beam), cataloguing 10,830 sources above 5 sigma, and enclosing the full 2 square degree COSMOS field. By combining these radio data with optical, near-infrared (UltraVISTA), and mid-infrared (Spitzer/IRAC) data, as well as X-ray data (Chandra), the authors find counterparts to radio sources for ~93% of the total radio sample in the unmasked areas of the COSMOS field, i.e., those not affected by saturated or bright sources in the optical to near-IR (NIR) bands, reaching out to z ~ 6. They further classify the sources as star-forming galaxies or AGN based on various criteria, such as X-ray luminosity, observed mid-infrare (MIR) color, UV-far-infrared (FIR) spectral-energy distribution (SED), rest-frame near-ultraviolet (NUV)-optical color corrected for dust extinction, and radio-excess relative to that expected from the the hosts' star-formation rate. The authors separate the AGN into sub-samples dominated by low-to-moderate and moderate-to-high radiative luminosity AGN, i.e., candidates for high-redshift analogs to local low- and high-excitation emission line AGN, respectively. They study the fractional contributions of these sub-populations down to radio flux levels of ~11 uJy at 3 GHz (or ~20 uJy at 1.4 GHz assuming a spectral index of -0.7), and find that the dominant fraction at 1.4 GHz flux densities above ~200 uJy is constituted of low-to-moderate radiative luminosity AGN MLAGN). Below densities of ~100 uJy the fraction of star-forming galaxies (SFG) increases to ~60%, followed by the moderate-to-high radiative luminosity AGN (HLAGN) with ~20%, and MLAGN with ~20%. Based on this observational evidence, the authors extrapolate the fractions down to sensitivities of the Square Kilometer Array (SKA). Their estimates suggest that at the faint flux limits to be reached by the (Wide, Deep, and UltraDeep) SKA1 surveys, a selection based only on radio flux limits can provide a simple tool to efficiently identify samples highly (>75%) dominated by star-forming galaxies. This table contains the full list of 9,161 optical-MIR counterparts collected over the largest unmasked area accessible to each catalog, being 1.77, 1.73, and 2.35 square degrees for COSMOS2015, i-band, and IRAC catalogs, respectively. The catalog lists the counterpart IDs, properties, as well as the individual criteria used in this work to classify these radio sources. The authors note that complete, non-overlapping samples within a well defined, effective area of 1.77 square degrees (COSMOS2015 masked area flag_C15 = 0, can be formed by combining (i) HLAGN, MLAGN, and clean SFG samples, or, alternatively, (ii) the radio-excess and no-radio-excess samples. This table was created by the HEASARC in July 2017 based on CDS Catalog J/A+A/602/A2 file table1.dat, the VLA-COSMOS 3-GHz Large Project multiwavelength counterpart catalog. This is a service provided by NASA HEASARC .
DEEP2 Galaxy Redshift Survey Fields Chandra Point Source Catalog
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This table contains the X-ray point-source catalog produced from the Chandra Advanced CCD Imaging Spectrometer (ACIS-I) observations of the combined ~3.2 deg2 DEEP2 (XDEEP2) survey fields, which consist of four ~ 0.7 - 1.1 deg2 fields. The combined total exposures across all four XDEEP2 fields range from ~ 10 ks to 1.1 Ms. The authors detect X-ray point sources in both the individual ACIS-I observations and the overlapping regions in the merged (stacked) images. They find a total of 2976 unique X-ray sources within the survey area with an expected false-source contamination of ~ 30 sources (<~ 1%). In their paper, the authors present the combined log N-log S distribution of sources detected across the XDEEP2 survey fields and find good agreement with the Extended Chandra Deep Field and Chandra-COSMOS fields to f_(X,0.5-2keV)_ ~ 2 x 10-16 erg cm-1 s-1. Given the large survey area of XDEEP2, they additionally place relatively strong constraints on the log N-log S distribution at high fluxes (f_(X,0.5-2keV) ~ 3 x 10-14 erg cm-1 s-1), and find a small systematic offset (a factor ~ 1.5) toward lower source numbers in this regime, when compared to smaller area surveys. The number counts observed in XDEEP2 are in close agreement with those predicted by X-ray background synthesis models. Additionally, the authors present a Bayesian-style method for associating the X-ray sources with optical photometric counterparts in the DEEP2 catalog (complete to RAB < 25.2) and find that 2126 (~ 71.4% +/- 2.8%) of the 2976 X-ray sources presented here have a secure optical counterpart with a <~ 6% contamination fraction. The present table provides the DEEP2 optical source properties (e.g., magnitude, redshift) as part of the X-ray-optical counterpart catalog. This table was created by the HEASARC in October 2012 based on electronic versions of Tables 5 and 7 from the reference paper which were obtained from the ApJS web site. This is a service provided by NASA HEASARC .
2XMMi/SDSS Galaxy Cluster Survey
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The authors have compiled a sample of X-ray-selected galaxy groups and clusters from the XMM-Newton Serendipitous Source Catalog (2XMMi-DR3) with optical confirmation and redshift measurement from the Sloan Digital Sky Survey (SDSS). In their paper, they present an analysis of the X-ray properties of this new sample with particular emphasis on the X-ray luminosity-temperature (LX - T) relation. The X-ray cluster candidates were selected from the 2XMMi-DR3 catalog in the footprint of the SDSS-DR7. The authors developed a finding algorithm to search for overdensities of galaxies at the positions of the X-ray cluster candidates in the photometric redshift space and to measure the redshifts of the clusters from the SDSS data. For optically confirmed clusters with good quality X-ray data, they derived the X-ray flux, luminosity, and temperature from proper spectral fits, while the X-ray flux for clusters with low-quality X-ray data was obtained from the 2XMMi-DR3 catalogue. The detection algorithm provides the photometric redshift of 530 galaxy clusters. Of these, 310 clusters have a spectroscopic redshift for at least one member galaxy. About 75 percent of the optically confirmed cluster sample are newly discovered X-ray clusters. Moreover, 301 systems are known as optically selected clusters in the literature while the remainder are new discoveries in X-ray and optical bands. The optically confirmed cluster sample spans a wide redshift range 0.03 to 0.70 (median z = 0.32). In this paper, they present the catalog of X-ray-selected galaxy groups and clusters from the 2XMMi/SDSS galaxy cluster survey. The catalog has two subsamples: (i) a cluster sample comprising 345 objects with their X-ray spectroscopic temperature and flux from the spectral fitting; (these objects are identified by having values for the table_sample parameter of 1 in this HEASARC implementation of the catalog) and (ii) a cluster sample consisting of 185 systems with their X-ray flux from the 2XMMi-DR3 catalog, because their X-ray data are insufficient for spectral fitting (these objects are identified by having values for the table_sample parameter of 2 herein). For each cluster, the catalog also provides the X-ray bolometric luminosity and the cluster mass at R500 based on scaling relations and the position of the likely brightest cluster galaxy (BCG). The updated LX - T relation of the current sample with X-ray spectroscopic parameters is presented in the paper. The authors found the slope of the LX - T relation to be consistent with published ones. They see no evidence for evolution in the slope and intrinsic scatter of the LX - T relation with redshift when excluding the low-luminosity groups. This catalog of X-ray selected galaxy clusters and groups supersedes and subsumes the first release of the 2XMMi/SDSS Galaxy Cluster Survey, comprising 175 clusters of galaxies, which was presented in Takey et al. (2011, A&A, 534, A120). This table was created by the HEASARC in October 2013 based on CDS catalog J/A+A/558/A75 files table1.dat and table2.dat. This is a service provided by NASA HEASARC .
VLA 74-MHz Deep High-Resolution Survey Source Catalog
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This table contains some of the results from a 74-MHz survey of a 165 deg2 region located near the North Galactic Pole (NGP). This survey has an unprecedented combination of both spatial resolution (25" FWHM) and sensitivity (1-sigma as low as 24mJy/beam). The authors detect 949 sources at the 5-sigma level in this region, enough to begin exploring the nature of the 74-MHz source population. In their paper, they present differential source counts, spectral index measurements, and the size distribution as determined from counterparts in the high-resolution FIRST 1.4-GHz survey. They find a trend of steeper spectral indices for the brighter sources. Further, there is a clear correlation between spectral index and median source size, with the flat-spectrum sources being much smaller on average. Ultra-steep spectrum objects (power-law index alpha <= -1.2, where S_nu ~ nualpha) are identified. These sources are excellent candidates for high-redshift radio galaxies. The data used to produce this survey come from observations taken on 1998 March 7 intended to map two normal galaxies at 74 MHz (NGC 4565 and NGC 4631). These two pointings were separated by 6.4 degrees, roughly the radius of the primary beam at 74 MHz, allowing them to be ideally combined to produce a single deep image roughly 17 x 10 degrees in size. The combination of VLA A-configuration resolution (25 arcsec), favorable ionospheric conditions, and pointings in directions near the NGP, where the background temperature is low, produced the deepest observation ever obtained below 100 MHz. The same algorithm that was used in the 1.4-GHz NVSS was used to identify and characterize sources in this 74-MHz survey. The source detection algorithm had a threshold such that sources must have both a peak and integrated flux density level of at least 5 times the local rms noise level. Since the rms noise level varied from 24 mJy/beam to 80 mJy mJy/beam at the chosen field edge, the absolute level of the source-detection threshold of 5-sigma likewise varied over the image. This table was created by the HEASARC in August 2010 based on CDS catalog J/ApJS/150/417/ file table2.dat. This is a service provided by NASA HEASARC .
Phoenix Deep Survey Optical and Near-Infrared Counterparts Catalog
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Using a deep Australia Telescope Compact Array (ATCA) radio survey covering an area of ~3 deg2 to a 4-sigma sensitivity of >= 100 µJy (µJy) at 1.4 GHz, the authors study the nature of faint radio galaxies. The region, 2 degrees in diameter and centered on RA and Dec (J2000.0) of 1h 14m 12.16s, -45o 44' 08.0" (Galactic latitude of -71o), is known as the Phoenix Deep Field. About 50% of the detected radio sources are identified with an optical counterpart revealed by CCD photometry to mR = 22.5 magnitudes. Near-infrared (K-band) data are also available for a selected sample of the radio sources, while spectroscopic observations have been carried out for about 40% of the optically identified sample. These provide redshifts and information on the stellar content. Emission-line ratios imply that most of the emission-line sources are star-forming galaxies, with a small contribution (~ 10%) from Seyfert 1/Seyfert 2 type objects. The authors also find a significant number of absorption-line systems, likely to be ellipticals. These dominate at high flux densities ( > 1 mJy) but are also found at sub-mJy levels. Using the Balmer decrement, they find a visual extinction AV = 1.0 for the star-forming faint radio sources. This moderate reddening is consistent with the (V - R) and (R - K) colors of the optically identified sources. For emission-line galaxies, there is a correlation between the radio power and the H-alpha luminosity, in agreement with the result of Benn et al. (1993, MNRAS, 263, 98). This suggests that the radio emission of starburst radio galaxies is a good indicator of star formation activity. When calculating luminosities, the authors assume a cosmology with a Hubble constant H0 of 50 km s-1 Mpc-1 and a deceleration parameter q0 of 0.5. This table was created by the HEASARC in June 2013 based on an electronic version of Table 1 from the reference paper, which details the photometric (optical and near-infrared), radio, spectroscopic and intrinsic properties of the faint radio sources in the PDS with established redshifts, which was obtained from the CDS web site (their catalog J/MNRAS/306/708 file table1.dat). This is a service provided by NASA HEASARC .
Large Bright Quasar Survey
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Positions, redshifts, and magnitudes for the 1055 quasars in the Large Bright Quasar Survey (LBQS) are presented in a single catalog. Celestial positions have been rederived using the PPM catalog to provide an improved reference frame. Redshifts calculated via cross correlation with a high signal-to-noise ratio composite quasar spectrum are included and the small number of typographic and redshift misidentifications in the discovery papers are corrected. Compared to the discovery papers (references below), 12 quasars that are either fainter than the field magnitude limit or fall outside the final survey area have been deleted, 12 quasars that were discovered subsequent to paper V have been added, 10 redshifts have been corrected, and 13 quasars with either incorrect or degenerate designations (LBQS names) have had their designations corrected. The information in this version of the LBQS Catalog is the same as in Table 4 of the published paper with the following exceptions: (i) the object 0021-0213 has a redshift of 2.348; this value was listed in Table 5 of the paper but was not incorporated in Table 4 of the paper; (ii) the parameter 'Reference' in Table 4 of the published paper (which specified in which paper in the LBQS series the quasar spectrum could be found) has been omitted; and (iii) the parameter 'Notes' in Table 4 of the published paper had two non-blank values: '+' and 'a'; in the HEASARC representation of this catalog we have replaced the Notes value of '+' by 'C', and dropped the Notes value of 'a' (used to indicate objects that had been listed as AGN in earlier papers). This catalog was created by the HEASARC in July 1999 based on a table that was kindly provided by the first author, Paul Hewett, supplemented by documentation created by the CDS/ADC. This is a service provided by NASA HEASARC .
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