/ftp/cats/I/247



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I/247   ==OBSOLETE version of Catalogue==
28-Dec-2001: (by Francois Ochsenbein) See AC2000.2 = I/275
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Query from: http://vizier.cds.unistra.fr/cgi-bin/VizieR?-source=I/247
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drwxr-xr-x 317 cats archive 8192 Feb 28 11:16 [Up] drwxr-xr-x 4 cats archive 4096 Jan 13 2023 [TAR file] -rw-r--r-- 1 cats archive 399 Dec 19 2022 .message -rw-r--r-- 1 cats archive 59 Dec 28 2001 =obsolete= -r--r--r-- 1 cats archive 7177 Nov 10 1998 ReadMe -r--r--r-- 1 cats archive 5264854 Nov 10 1998 ac_n00.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 7118668 Nov 10 1998 ac_n10.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 7121594 Nov 10 1998 ac_n20.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 6611275 Nov 10 1998 ac_n30.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 8470239 Nov 10 1998 ac_n40.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 6730791 Nov 10 1998 ac_n50.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 6695521 Nov 10 1998 ac_n60.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 5704326 Nov 10 1998 ac_p00.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 5935805 Nov 10 1998 ac_p10.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 6653583 Nov 10 1998 ac_p20.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 7269105 Nov 10 1998 ac_p30.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 4129730 Nov 10 1998 ac_p40.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 4775693 Nov 10 1998 ac_p50.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 5268423 Nov 10 1998 ac_p60.dat.gz [txt] [txt.gz] [fits] [fits.gz] [html] -r--r--r-- 1 cats archive 91990 Nov 8 1998 intro.tex drwxr-xr-x 2 cats archive 155 Sep 25 2003 ps
Beginning of ReadMe : I/247 The AC2000 Catalogue (Urban+ 1997) ================================================================================ The AC2000: the Astrographic Catalogue on the Hipparcos System Urban S.E., Corbin T.E., Wycoff G.L. <US Naval Observatory (1997)> ================================================================================ ADC_Keywords: Positional data ; Astrographic zones ; Surveys Description: The Astrographic Catalogue (AC) was an international effort designed to photograph and measure the positions of all stars brighter than magnitude 11.0. In total, some 4.6 million stars were observed, many as faint as 13th magnitude. Users should realize that a few thousand of the brightest stars are not included; their images on the source plates were grossly over-exposed and therefore measurements were often not made. This project was started over 100 years ago, and the positions that have been derived from the AC data are being used, in combination with modern epoch positions, to determine accurate proper motions. The United States Naval Observatory has completed the reductions of the Astrographic Catalogue data (AC) to a consistent system. The resulting catalog, called AC 2000, contains 4,621,836 stars covering the entire sky, at an average epoch of 1907. The positions are on the Hipparcos reference frame (J2000.0) at the epochs of observation. Each of the 22 zones making up the Astrographic Catalogue was reduced independently using the Astrographic Catalog Reference Stars (ACRS). Each was analyzed for tilt, radial and tangential distortions, coma, magnitude equation and non-symmetric field distortions. Following these reductions, the data were placed on the Hipparcos system and the magnitudes were converted to be close to that of the Tycho B data. The resulting data were then combined into the final catalog. Detailed information on the reduction methodology and input data can be found in the file "intro.tex", or in the postscript documents provided provided in the "ps" subdirectory. The data contain the positions (eq. J2000.0) at mean epochs of observation, magnitude estimates and accuracy estimates for each star. Cross identifications with the Hipparcos Catalogue, Tycho Catalogue and the Astrographic Catalog Reference Stars are provided to facilitate future work with these stars. Interested parties are encouraged to visit the AC web site at http://aries.usno.navy.mil/ad/ac.html.