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691. Quasars and Active Galactic Nuclei (13th Ed.)
ID:
ivo://CDS.VizieR/VII/258
Title:
Quasars and Active Galactic Nuclei (13th Ed.)
Short Name:
VII/258
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalogue is a compilation of all known AGNs presented in a compact and convenient form. It is an update of the previous versions; and as in the previous editions no information about absorption lines of X-ray properties are given, but absolute magnitudes are given, assuming Ho=71km/s/Mpc and q_0_=0 (notice the change of cosmology: Ho was assumed to be 50km/s/Mpc in the previous editions). When available, the 20cm and 6cm radio flux are given. The present edition of this catalogue contains the quasars with measured redshift known prior to July 1st, 2009. It contains 133336 quasars, 1374 BL Lac objects and 34231 active galaxies (including 15627 Seyfert 1's), almost doubling the number listed in the 12th edition. Lists of known lensed quasars (table2.dat) and double quasars (table3.dat) are also given here.
692. Quasars and Active Galactic Nuclei (9th Ed.)
ID:
ivo://CDS.VizieR/VII/215
Title:
Quasars and Active Galactic Nuclei (9th Ed.)
Short Name:
VII/215
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalogue is an update of the previous versions. It contains 13214 (+1856) quasars (defined as brighter than absolute B magnitude -23), 4428 (+1094) AGNs (defined as fainter than absolute B magnitude -23) and 462 (+105) BL Lac objects from 2054 (+191) references.
693. Quasars and Active Galactic Nuclei (10th Ed.)
ID:
ivo://CDS.VizieR/VII/224
Title:
Quasars and Active Galactic Nuclei (10th Ed.)
Short Name:
VII/224
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalogue is an update of the previous versions. The recent publication of the first release of the 2dF quasar survey (Croom et al., 2001MNRAS.322L..29C, see Cat. <VII/223>) containing nearly 10,000 new QSOs, almost doubled the number of known such objects: there are now 23760 (+10546) quasars (defined as brighter than absolute B magnitude -23), 5751 (+1323) AGNs (defined as fainter than absolute B magnitude -23) of which 2765 are Seyfert 1, and 608 (+146) BL Lac objects from 2173 (+119) references. Like the ninth edition, it includes position and redshift as well as photometry (U, B, V) and 6 and 11 cm flux densities when available. The present edition this catalogue contains the quasars with measured redshift known prior to May 1st, 2001.
694. Quasars and Active Galactic Nuclei (8th Ed.)
ID:
ivo://CDS.VizieR/VII/207
Title:
Quasars and Active Galactic Nuclei (8th Ed.)
Short Name:
VII/207
Date:
21 Oct 2021
Publisher:
CDS
Description:
This catalogue is an update of the previous versions. It contains 11358 (+2759) quasars (defined as brighter than absolute B magnitude -23), 3334 (+501) AGNs (defined as fainter than absolute B magnitude -23) and 357 (+137) BL Lac objects from 1863 (+201) references.
695. Quasars and Active Galactic Nuclei (8th Ed.)
ID:
ivo://org.gavo.dc/veronqsos/q/data
Title:
Quasars and Active Galactic Nuclei (8th Ed.)
Short Name:
veronqsos.data
Date:
27 Dec 2024 08:31:02
Publisher:
The GAVO DC team
Description:
This catalogue (with updates to the pervious version) contains 11358 (+2759) quasars (defined as brighter than absolute B magnitude -23), 3334 (+501) AGNs (defined as fainter than absolute B magnitude -23) and 357 (+137) BL Lac objects from 1863 (+201) references.
696. Quasars as standard candles. III.
ID:
ivo://CDS.VizieR/J/A+A/642/A150
Title:
Quasars as standard candles. III.
Short Name:
J/A+A/642/A150
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a new catalogue of ~2400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM-Newton. The sample can be used to investigate the non-linear relation between the UV and X-ray luminosity of quasars, and to build a Hubble diagram up to redshift z~7.5. We selected sources that are neither reddened by dust in the optical/UV nor obscured by gas in the X-rays, and whose X-ray fluxes are free from flux-limit related biases. After checking for any possible systematics, we confirm, in agreement with our previous works, that (i) the X-ray to UV relation provides distance estimates matching those from supernovae up to z~1.5, and (ii) its slope shows no redshift evolution up to z~5. We provide a full description of the methodology for testing cosmological models, further supporting a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat LambdaCDM model up to z~1.5-2, but strong deviations emerge at higher redshifts. Since we have minimized all non-negligible systematic effects, and proven the stability of the Lx-Lo relation at high redshifts, we conclude that an evolution of the expansion rate of the Universe should be considered as a possible explanation for the observed deviation, rather than some systematic (redshift-dependent) effect associated with high-redshift quasars.
697. Quasars behind the Magellanic system
ID:
ivo://CDS.VizieR/J/A+A/549/A29
Title:
Quasars behind the Magellanic system
Short Name:
J/A+A/549/A29
Date:
21 Oct 2021
Publisher:
CDS
Description:
The number and spatial distribution of confirmed quasi-stellar objects (QSOs) behind the Magellanic system is limited. This undermines their use as astrometric reference objects for different types of studies. We have searched for criteria to identify candidate QSOs using observations from the VISTA survey of the Magellanic Clouds system (VMC) that provides photometry in the YJKs bands and 12 epochs in the Ks band. The (Y-J) versus (J-Ks) diagram has been used to distinguish QSO candidates from Milky Way stars and stars of the Magellanic Clouds. Then, the slope of variation in the Ks band has been used to identify a sample of high confidence candidates. These criteria were developed based on the properties of 117 known QSOs presently observed by the VMC survey.
698. Quasars from 7C survey
ID:
ivo://CDS.VizieR/J/MNRAS/307/293
Title:
Quasars from 7C survey
Short Name:
J/MNRAS/307/293
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe the selection of candidate radio-loud quasars obtained by cross-matching radio source positions from the low-frequency (151-MHz) 7C survey with optical positions from five pairs of EO POSS-1 plates scanned with the Cambridge Automatic Plate-measuring Machine (APM). The sky region studied is centred at RA=10h28m, DE=+41{deg} and covers ~0.057sr. We present VLA observations of the quasar candidates, and tabulate various properties derived from the radio maps. We discuss the selection criteria of the resulting '7CQ' sample of radio-loud quasars. The 70 confirmed quasars, and some fraction of the 36 unconfirmed candidates, constitute a filtered sample with the following selection criteria: 151-MHz flux density S_151_>100mJy; POSS-I E-plate magnitude E~R<20; POSS-I colour (O-E)<1.8; the effective area of the survey drops significantly below S_151_~200mJy. We argue that the colour criterion excludes few if any quasars, but note, on the basis of recent work by Willott et al. (1998MNRAS.300..625W), that the E magnitude limit probably excludes more than 50 per cent of the radio-loud quasars.
699. Quasars from SDSS-DR7, WISE and UKIDSS surveys
ID:
ivo://CDS.VizieR/J/AJ/144/49
Title:
Quasars from SDSS-DR7, WISE and UKIDSS surveys
Short Name:
J/AJ/144/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalog of 37842 quasars in the Sloan Digital Sky Survey (SDSS) Data Release 7, which have counterparts within 6" in the Wide-field Infrared Survey Explorer (WISE) Preliminary Data Release. The overall WISE detection rate of the SDSS quasars is 86.7%, and it decreases to less than 50.0% when the quasar magnitude is fainter than i=20.5. We derive the median color-redshift relations based on this SDSS-WISE quasar sample and apply them to estimate the photometric redshifts of the SDSS-WISE quasars. We find that by adding the WISE W1- and W2-band data to the SDSS photometry we can increase the photometric redshift reliability, defined as the percentage of sources with photometric and spectroscopic redshift difference less than 0.2, from 70.3% to 77.2%. We also obtain the samples of WISE-detected normal and late-type stars with SDSS spectroscopy, and present a criterion in the z-W1 versus g-z color-color diagram, z-W1>0.66(g-z)+2.01, to separate quasars from stars. With this criterion we can recover 98.6% of 3089 radio-detected SDSS-WISE quasars with redshifts less than four and overcome the difficulty in selecting quasars with redshifts between 2.2 and 3 from SDSS photometric data alone. We also suggest another criterion involving the WISE color only, W1-W2>0.57, to efficiently separate quasars with redshifts less than 3.2 from stars. In addition, we compile a catalog of 5614 SDSS quasars detected by both WISE and UKIDSS surveys and present their color-redshift relations in the optical and infrared bands. By using the SDSS ugriz, UKIDSS, YJHK, and WISE W1- and W2-band photometric data, we can efficiently select quasar candidates and increase the photometric redshift reliability up to 87.0%. We discuss the implications of our results on the future quasar surveys. An updated SDSS-WISE quasar catalog consisting of 101853 quasars with the recently released WISE all-sky data is also provided.
700. Quasars in ESO/SERC field 927
ID:
ivo://CDS.VizieR/J/MNRAS/266/317
Title:
Quasars in ESO/SERC field 927
Short Name:
J/MNRAS/266/317
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the spectroscopic observations of 56 quasars that were discovered by AQD (Automated Quasar Detection) in a field of ~25.3deg2, centred at (1950) RA l0h40m00s, Dec. 05deg00'00". These observations, with the CTIO 4-m telescope, led to the discovery by Clowes & Campusano of a large group of quasars with size ~100-200h^-1^Mpc at z~1.3. Quasars of particular interest are noted, including one that is a BAL quasar with z~1.78.