The construction of the large quasar astrometric catalogue (LQAC)

Souchay, J.; Andrei, A. H.; Barache, C.; Bouquillon, S.; Gontier, A. M.; Lambert, S.; Poncin-Lafitte, Christophe Le; Taris, F.; Arias, E. F.; Suchet, Daniel; Baudin, Mathieu

doi:10.1051/0004-6361:200809602

Cited by 32 publications

(37 citation statements)

References 34 publications

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“…=1.5-3.0s trans. is used for rejecting outliers (Hog et al 1994, p. 71;Souchay et al 2009). However, due to the small number of matched pairs in our images, the astrometric solutions are sensitive to individual pairs and a single mismatched pair can affect our conclusions.…”

Section: Computing the Coordinate Transformationsmentioning

confidence: 99%

Spatially Offset Active Galactic Nuclei. I. Selection and Spectroscopic Properties

Barrows

Comerford

Greene

et al. 2016

ApJ

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We present a sample of 18optically selected and X-ray-detected spatially offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS). In ninesystems, the X-ray active galactic nucleus (AGN) is spatially offset from the galactic stellar core that is located within the 3″ diameter SDSS spectroscopic fiber. In 11systems, the X-ray AGN is spatially offset from a stellar core that is located outside the fiber, with an overlap of two. To build the sample, we cross-matched Type II AGNs selected from the SDSS galaxy catalog with archival Chandra imaging and employed our custom astrometric and registration procedure. The projected angular (physical) offsets span a range of 0 6 (0.8 kpc) to 17 4 (19.4 kpc), with a median value of 2 7 (4.6 kpc). The offset nature of an AGN is an unambiguous signature of a galaxy merger, and these systems can be used to study the properties of AGNs in galaxy mergers without the biases introduced by morphological merger selection techniques. In this paper (Paper I), we use our sample to assess the kinematics of AGN photoionized gas in galaxy mergers. We find that spectroscopic offset AGN selection may be up to -+ 89 16 7 % incomplete due to small projected velocity offsets. We also find that the magnitude of the velocity offsets are generally larger than expected if our spatial selection introduces a bias toward face-on orbits, suggesting the presence of complex kinematics in the emission line gas of AGNs in galaxy mergers.

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Section: Computing the Coordinate Transformationsmentioning

confidence: 99%

Spatially Offset Active Galactic Nuclei. I. Selection and Spectroscopic Properties

Barrows

Comerford

Greene

et al. 2016

ApJ

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“…Mortlock et al (1999) stress the difficulty sometimes encountered in distinguishing lensed quasars from physical pairs. Souchay et al (2009) have recently published a catalogue of 113 666 "quasars" by compiling a number of published optical and radio catalogues. As a result this is not, stricktly speaking, a quasar catalogue because several of the included objects (2921) have no optical identification or measured redshift.…”

Section: Description Of the Cataloguementioning

confidence: 99%

A catalogue of quasars and active nuclei: 13th edition

Véron-Cetty

Véron

2010

A&A

677

298

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Aims. This catalogue is aimed at presenting a compilation of all known AGN in a compact and convenient form, and we hope that it will be useful to all workers in this field. Methods. Like the twelfth edition, it includes position and redshift, as well as photometry (U, B, V) and 6 cm and 20 cm flux densities, when available.Results. The present version contains 133 336 quasars, 1 374 BL Lac objects, and 34 231 active galaxies (including 16 517 Seyfert 1s), almost doubling the number listed in the 12th edition. We also give a list of all known lensed and double quasars.

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“…To fill this gap, Souchay et al (2009) produced their own compiled catalogue highlighting the astrometric properties of quasars, in particular by an optimized selection of celestial coordinates. This first version in Souchay et al (2009) contained 113 666 objects and the last version, called LQAC-3, gathered 321 957 objects (Souchay et al 2015).…”

Section: Introductionmentioning

confidence: 99%

“…This first version in Souchay et al (2009) contained 113 666 objects and the last version, called LQAC-3, gathered 321 957 objects (Souchay et al 2015). Since 2010 and the final version of the Véron-Cetty & Véron (2010) catalogue, Souchay et al (2009) pursued the goal of gathering the overall known quasars population from all the available surveys in a unique catalogue with both astrometric and astrophysical data.…”

Section: Introductionmentioning

confidence: 99%

LQAC-4: Fourth release of the Large Quasar Astrometric Catalogue

Gattano

Andrei

Coelho

et al. 2018

A&A

Self Cite

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Context. From an astrometric point of view, quasars constitute the best and almost ideal reference objects in the celestial sphere, with a priori no significant proper motion. Since the third release of the Large Quasar Astrometric Catalogue (LQAC-3), a large number of quasars have been discovered, in particular those coming from the DR12Q release of the SDSS. Moreover, for cross-matched objects, we have taken advantage of the very accurate determinations of the quasars identified within the recent Gaia DR1 catalogue. Aims. Following the same procedure as in the three previous releases of the LQAC, our aim is to compile the large majority of all the quasars recorded so far. Our goal is to record their best coordinates and substantial information concerning their physical properties such as the redshift as well as multi-bands apparent and absolute magnitudes. Emphasis is given to the results of the cross-matches with the Gaia DR1 catalogue. Methods. New quasars coming from the DR12Q release were cross-matched with the precedent LQAC-3 compilation with a 1 search radius, in order to add the objects without counterpart to the LQAC-4 compilation. A similar cross-match was done with Gaia DR1 to identify the known quasars detected by Gaia. This enables one to improve significantly the positioning of these objects, and in parallel to study the astrometric performance of the individual catalogues of the LQAC-4 compilation. Finally, a new method was used to determine absolute magnitudes. Results. Our final catalogue, called LQAC-4, contains 443 725 objects. This is roughly 37.82% more than the number of objects recorded in the LQAC-3. Among them, 249 071 were found in common with the Gaia DR1, with a 1 search radius. That corresponds to 56.13% of the whole population in the compilation. Conclusions. The LQAC-4 delivers to the astronomical community a nearly complete catalogue of spectroscopically confirmed quasars (including a small proportion of compact AGNs), with the aim of giving their best equatorial coordinates with respect to the ICRF2 and with exhaustive additional information. For more than 50% of the sample, these coordinates come from the very recent Gaia DR1.

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The construction of the large quasar astrometric catalogue (LQAC)

Cited by 32 publications

References 34 publications

Spatially Offset Active Galactic Nuclei. I. Selection and Spectroscopic Properties

Spatially Offset Active Galactic Nuclei. I. Selection and Spectroscopic Properties

A catalogue of quasars and active nuclei: 13th edition

LQAC-4: Fourth release of the Large Quasar Astrometric Catalogue

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