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Detailed Description of I/255
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Individual files can be fetched (via http) from
here
or via ftp from: ftp://cdsarc.u-strasbg.fr/pub/cats/I/255
The catalogue can be queried from: http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/255
This standardized document follows the rules of the Standard Description for Astronomical Catalogues. For those having to work on this catalogue using FORTRAN programs, this ReadMe file can be transformed into a f77-compliant program which reads the files making up this catalogue, in two versions: either a f77 program loading whole files into arrays, or a f77-program reading each data file line by line.
I/255 The HST Guide Star Catalog, Version GSC-ACT (Lasker+ 1996-99)
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The Guide Star Catalog Version 1.1-ACT (GSC-ACT Catalogue)
Lasker B.M., Russel J.N., Jenkner H.
<The Association of Universities for Research in Astronomy, Inc.
([c] 1989, 1992, 1996)>
================================================================================
The Guide Star Catalog Version 1.0 is described in a series of papers:
I. Astronomical foundations and image processing
Lasker B.M., Sturch C.R., McLean B.J., Russell J.L., Jenkner H., Shara M.M.
<Astron. J., 99, 2019 (1990)>
=1990AJ.....99.2019L
II. Photometric and astrometric models and solutions
Russell J.L., Lasker B.M., McLean B.J., Sturch C.R., Jenkner H.
<Astron. J., 99, 2059-2081 (1990)>
=1990AJ.....99.2059R
III. Production, database organization, and population statistics
Jenkner H., Lasker B.M., Sturch C.R., McLean B.J., Shara M.M., Russell J.L.
<Astron. J., 99, 2082 (1990)>
=1990AJ.....99.2082J
ADC_Keywords: Surveys ; Positional data
Description:
The Guide Star Catalog (GSC), which has been constructed to support
the operational need of the Hubble Space Telescope contains nearly 19
million objects brighter than sixteenth magnitude, of which more than
15 million are classified as stars. This catalog provides positions
and magnitudes for these stars.
The original version of this catalog, GSC 1.0, is described in a
series of papers: Lasker et al. (1990AJ.....99.2019L);
Russell et al. (1990AJ.....99.2059R); and
Jenkner et al. (1990AJ.....99.2082J)
The reference material for the GSC 1.2 reduction is the "Positions and
Proper Motions Catalogue":
PPM-North, Roeser S. and Bastian U., 1988, Cat. I/146
PPM-South, Bastian U. and Roeser S., 1993, Cat. I/193
PPM-Suppl, Roeser S., Bastian U. and Kuzmin A., 1994, Cat. I/208
and the Astrographic Catalogue (AC) which was used to remove the mean
systematics common to all the plates.
The GSC GSC-ACT is a recalibration of GSC1.1 using the ACT
(Astrographic Catalog/Tycho, catalog I/246) performed by the Project
Pluto ("See also" section below). The "plate RMS" values are given at
http://www.projectpluto.com/results.txt, with most plates coming in at
under .3 arcseconds
File Summary:
FileName Lrecl Records Explanations
× ReadMe 80 . This file
× regions.dat 47 9537 The corners of each small region
× GSC/* 0 . Compact version of GSC (for Unix or Linux)
× out.sam 68 100 Sample output (out of 25,258,765 positions)
See also:
http://www-gsss.stsci.edu/gsc/gsc.html : GSC pages at STScI
I/220 : The HST Guide Star Catalog, Version 1.1 (Lasker+ 1992)
I/254 : The HST Guide Star Catalog, Version 1.2 (Lasker+ 1992)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
I/246 : The ACT Reference Catalog (Urban+ 1997)
I/250 : The Tycho Reference Catalogue (Hog+ 1998)
http://www.projectpluto.com/gsc_act.htm : GSC-ACT Original Description
Byte-by-byte Description of file: out.sam
Bytes Format Units Label Explanations
1- 10 I10 --- GSC *GSC designation
12- 20 F9.5 deg RAdeg Right ascension in J2000, epoch of plate
22- 30 F9.5 deg DEdeg Declination in J2000, epoch of plate
33- 36 F4.1 arcsec PosErr Mean error on position
38- 42 F5.2 mag Pmag photographic magnitude (see n_Pmag)
44- 47 F4.2 mag e_Pmag Mean error on photographic magnitude
49- 50 I2 --- n_Pmag *[0,18] Coded passband for magnitude
52 I1 --- Class [0,3] Class of object (0=star; 3=non-stellar)
54- 57 A4 --- Plate *Plate designation
59- 66 F8.3 yr Epoch *? Epoch of plate
68 A1 --- Mult [TF] True if multiple object / False otherwise
Note on GSC: the GSC Identification is made of a plate number
(5 digits) and star number on the plate (5 digits); note that,
in the literature, a dash separates generally the two parts.
Note on n_Pmag: the number designates the following combination
of emulsion and filter:
magband emulsion filter Notes
------- -------- -------- -----------------------
0 IIIaJ GG395 SERC-J/EJ
1 IIaD W12 Pal Quick-V
3 --- B Johnson
4 --- V Johnson
5 IIIaF RG630 Red
6 IIaD GG495 Pal QV/AAO XV
7 103aO --- POSS-I Blue
8 103aE red plex POSS-I Red
10 IIaD GG495 GPO Astrograph
11 103aO GG400 Black Birch Astrograph
16 IIIaJ GG495 QV
18 IIIaJ GG385 POSS-II Blue
------- -------- -------- -----------------------
Note on Plate, Epoch: two plates (+056 and +017) represent data from
catalogues (mainly Hipparcos Input Catalogue, Cat. I/196).
They have no associated epoch.
Byte-by-byte Description of file: regions.dat
Bytes Format Units Label Explanations
1- 5 I5 --- num Number of region
7- 8 I2 h RA0h Low limit of right ascension, hours (J2000)
10- 11 I2 min RA0m Low limit of right ascension, minutes (J2000)
13- 17 F5.2 s RA0s Low limit of right ascension, seconds (J2000)
19- 20 I2 h RA1h High limit of right ascension, hours (J2000)
22- 23 I2 min RA1m High limit of right ascension, minutes (J2000)
25- 29 F5.2 s RA1s High limit of right ascension, seconds (J2000)
31 A1 --- DE0- Low limit of declination, sign (J2000)
32- 33 I2 deg DE0d Low limit of declination, degrees (J2000)
35- 38 F4.1 arcmin DE0m Low limit of declination, minutes (J2000)
40 A1 --- DE1- High limit of declination, sign (J2000)
41- 42 I2 deg DE1d High limit of declination, degrees (J2000)
44- 47 F4.1 arcmin DE1m High limit of declination, minutes (J2000)
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(End) Bill Gray [Project Pluto], Francois Ochsenbein [CDS] 15-Sep-1999
