I/96 Astrographic Catalogue, +01 to +31 Degrees (Fresneau 1983)
Survey of the Astrographic Catalogue from 1 to 30 degrees of northern
declination
Fresneau A.
<Astron. Journ. 88, 1378 (1983)>
=1983AJ.....88.1378F 1983AJ.....88.1378F
ADC_Keywords: Astrographic zones; Positional data; Magnitudes, photographic
Description:
This machine-readable version of the Astrographic Catalogue (AC),
zones +01 to +31 degrees is the result of the determination of mean
values for position and magnitude at a mean epoch of observation for
each unique star in the original catalogs. The zones considered here
(Oxford, Paris, Bordeaux, Toulouse, Algiers [partial]) contained
1,870,976 individual measures, from which the catalog of mean data for
1,025,208 stars was derived. Further analysis by Dr. D.W. Dunham and
at the ADC yielded an additional 27897 apparently duplicate entries,
which were eliminated to produce the final catalog. The estimated mean
standard errors for positional and magnitude data are 0.4 arcsec in
each coordinate and 0.4 mag, respectively. Data in this version
include <m(pg)>, <Epoch>, at mean epoch, at mean epoch. The
mean values are unweighted. No star identifications are provided;
hence the user must select stars from the catalog and then identify
them in other catalogs or on charts using the equatorial coordinates.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
astrgrpc.dat 26 997311 The catalog
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Byte-by-byte Description of file: astrgrpc.dat
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Bytes Format Units Label Explanations
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1- 8 F8.4 deg RAdeg Right ascension at mean epoch given (1950.0)
9- 15 F7.4 deg DEdeg Declination at mean epoch given (1950.0)
16- 19 F4.1 mag Pmag *?=99.9 Mean photographic magnitude.
20- 26 F7.2 yr Epoch *Mean epoch of all observations for this star
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Note on Pmag:
The magnitude was set to 99.9 for four stars (see "History" section below)
Note on Epoch:
unweighted mean epoch
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Remarks and Modifications:
The machine-readable AC Survey +01 deg to +31 deg was prepared from a
tape supplied by the author (A. Fresneau) during a visit to the
Astronomical Data Center (ADC) on 21 July 1983. As received, the file
was found immediately to contain some stars at various right
ascensions which were apparently appended to the file; however, a copy
of the unsorted file was supplied to R. L. Millis of Lowell
Observatory, where he and L. H. Wasserman found additional groups of
stars out of RA order. The arrangement of the data was a result of the
reduction procedure (Fresneau 1983c) and should not have been
unexpected. Since the stars should be in some kind of rigorous order
for data searching purposes, the file was sorted by increasing RA with
decreasing DEC as the secondary sort field and increasing magnitude as
the tertiary sort field. A copy of the sorted file was then supplied
to D. W. Dunham, who discovered 19873 records where all data were
identical and 8024 records where differences were too small to be
accounted for by duplicity at AC resolution. A separation criterion of
0.00031 deg was used to eliminate all stars whose positions matched to
within the limit in both RA and DEC. Since Dunham also changed some of
the faint magnitudes to suit his own applications, only his program to
eliminate duplicates was used to process the original sorted version
to produce the present file with no magnitude modifications and the
revised format. Although a more detailed analysis may be performed
later, Dr. Warren concurs with the present method and production of
this file for distribution until such time as improved criteria may be
established. It is important to note and consider the fact that there
are quite a few stars present having magnitudes in the 16-18 range and
others for which punching errors have occurred, resulting in
magnitudes such as 79.3, 79.5, 26.0, 75.3, 49.5, etc. (77 stars
fainter than 16 magnitude, including definite punching errors). These
errors have not been corrected in the present machine version.
History:
* 28-Dec-1999: magnitudes which apparently resulted from means made with
unknown (99.9) values were set to 99.9. This concerns the records:
203537 (79.3) 238884 (79.5) 669552 (75.3) 796753 (49.5)
(F. Ochsenbein, CDS)
Acknowledgements:
Appreciation is expressed to A. Fresneau for making the
machine-readable catalog available for distribution from the ADC and
for reviewing and commenting on a preliminary version of this
document. L. H. Wasserman and D. W. Dunham kindly transmitted their
findings back to the ADC, and Dr. Dunham supplied his program for
elimination of duplicate entries and a copy of his modified version,
formatted specifically for ADC purposes. The combined efforts of these
colleagues have produced an improved version of the machine catalog
for distribution to the astronomical community. The original ADC
documentation by Wayne H. Warren, Jr. (1983) was used to create this
ReadMe file. Dr. Warren was also responsible for the preparation of
the catalog for archiving as described above.
References:
Fresneau A. 1983a, Astron. J. 88, 1378.
Fresneau A. 1983b, Proc. Statistical Methods in Astronomy Symposium,
Strasbourg, 13-16 September (ESA SP-201), p. 17.
Fresneau A. 1983c, personal communication.
(End) M.C. Larkin [SSDOO/ADC] C.-H. Joseph Lyu [Hughes STX/NASA] 08-Mar-1996