NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-04-21 T23:08:05 PDT
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For refcode 2015A&A...583A..75S:
There are 173675 NED objects in this reference.
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NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
2015A&A...583A..75S The third release of the Large Quasar Astrometric Catalog (LQAC-3): a compilation of 321 957 objects Souchay, J.; Andrei, A. H.; Barache, C.; Kalewicz, T.; Gattano, C.; Coelho, B.; Taris, F.; Bouquillon, S.; Becker, O. Abstract. Context. From an astrometric point of view, quasars constitute quasi-ideal reference objects in the celestial sphere, with an a priori absence of proper motion. Since the second release of the Large Quasar Astrometric Catalog (LQAC), a large number of quasars have been discovered, in particular with the upcoming new release of the SDSS quasars catalog. Aims: Following the same procedure as in the two previous releases of the LQAC, our aim was to compile all the quasars recorded until the present date, with accurate recomputation of their equatorial coordinates in the ICRS and with the maximum of information concerning their physical properties, such as the redshift, the photometry, and the absolute magnitudes. Methods: For the purpose above, we carried out the cross-identification between the 9 catalogs of quasars chosen for their huge number of objects, including all the available data related to magnitudes, radiofluxes, and redshifts. This cross identification was particularly delicate because of a slight change in coordinates between the objects common to two successive releases of the SDSS and the elimination of some of them. Equatorial coordinates were recomputed more accurately according to the algorithms used for the elaboration of the Large Quasar Reference Frame (LQRF). Moreover, absolute magnitudes and morphological indexes of the new objects were given, following the same method as in the LQAC-2. Results: Our final catalog, called LQAC-3, contains 321 957 objects including a small proportion of AGNs (14 128) and BLLac (1183). This is roughly 70% more than the number of objects recorded in the LQAC-2. Conclusions: The LQAC-3 will be useful for the astronomical community since it gives the most complete information available about the whole set of already recorded quasars, with emphasis on the precision and accuracy of their coordinates with respect to the ICRF2. The catalog is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/583/A75 Key words: catalogs, astrometry, reference systems, quasars: general, astronomical databases: miscellaneous
There are 173675 NED objects in this reference.
Please click here for ADS abstract

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