/ftp/cats/i/313



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I/313               LQRF: Large Quasar Reference Frame           (Andrei+, 2009)
The following files can be converted to FITS (extension .fit or fit.gz)
	lqrf.dat
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Query from: http://vizier.cds.unistra.fr/viz-bin/VizieR?-source=I/313
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drwxr-xr-x 317 cats archive 8192 Feb 28 11:16 [Up] drwxr-xr-x 2 cats archive 281 Jan 12 2023 [TAR file] -rw-r--r-- 1 cats archive 458 Dec 19 2022 .message -r--r--r-- 1 cats archive 5668 Dec 10 2009 ReadMe -rw-r--r-- 1 cats archive 2745 Jan 18 2010 +footg5.gif -rw-r--r-- 1 cats archive 25679 Jan 18 2010 +footg8.gif -r--r--r-- 1 cats archive 1809824 May 28 2009 lqrf.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html]
Beginning of ReadMe : I/313 LQRF: Large Quasar Reference Frame (Andrei+, 2009) ================================================================================ The LQRF - An optical representation of the ICRS. Andrei A.H., Souchay J., Zacharias N., Smart R.L., Vieira Martins R., da Silva Neto D.N., Camargo J.I.B., Assafin M., Barache C., Bouquillon S., Penna J.L., Taris, F. <Astron. Astrophys. 505, 385 (2009)> =2009A&A...505..385A ================================================================================ ADC_Keywords: QSOs ; Positional data Keywords: catalogs - reference systems - quasars: general - methods: data analysis - astrometry Abstract: The LQRF (Large Quasar Reference Frame) was built with the care of avoiding wrong matches of its constituents quasars, of homogenizing the astrometry from the different catalogs and lists from which the constituent quasars are gathered, and of attaining the milli-arcsec global alignment to the ICRF (International Celestial Reference Frame), as well as typical individual source position accuracies even to better than 100 milli-arcsec. Starting from the updated and presumably complete LQAC (Large Quasar Astrometric Catalog) list of QSOs, initial optical positions for those quasars are found in the USNO B1.0 and GSC2.3 catalogs, and from the SDSS Data Release 5. The initial positions are next placed onto UCAC2 based reference frames, following by an alignment to the ICRF, as well as of the most precise sources from the VLBA calibrator list and from the VLA calibrator list - when reliable optical counterparts exist. Finally the LQRF axes are inspected through spherical harmonics, contemplating right ascension, declination and magnitude terms. Description: The LQRF contains J2000 referred equatorial coordinates, and is completed by redshift and photometry information from the LQAC.The LQRF contains 100,165 quasars, well represented on all-sky basis, from -83.5 to +88.5 degrees of declination, and with 10-arcmin as the average distance between adjacent elements. The global alignment to the ICRF is of 1.5mas, and the individual position accuracies are represented by a Poisson distribution peaking at 139mas on right ascension and at 130mas on declination.