ACDS V10.0 - Tue May 26 13:51:07 CEST 2020
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Detailed Description of I/305 :
The Guide Star Catalog, Version 2.3.2 (GSC2.3) (STScI, 2006)
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Note : this is the description file of the original catalog.
This HTML page corresponds well to the original description, but some minor
changes in the format may have been introduced in the FITS output
files in order to allow for arithmetic operations on quantities
such as coordinates and times. h:m:s and d:m:s units are normally
converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the
units; the value given in the HTML files supersedes the value indicated in the ReadMe
file for this catalogue.
I/305 The Guide Star Catalog, Version 2.3.2 (GSC2.3) (STScI, 2006)
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The Guide Star Catalogue, Version 2.3.2
Lasker B., Lattanzi M.G., McLean B.J., et al.
<Astron. J. 136, 735 (2008)>
=2008AJ....136..735L
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ADC_Keywords: Surveys ; Positional data ; Magnitudes, photographic ; Morphology
Description:
The GSC II is an all-sky catalog based on 1" resolution scans of the
photographic Sky Survey plates, at two epochs and three bandpasses,
from the Palomar and UK Schmidt telescopes (DSS). Positions,
magnitudes, and classifications are produced for all objects on each
plate. The objects are then loaded into the COMPASS database, where
multiple observations of the same object are matched and assigned a
unique name.
The GSC2.3 has no magnitude limit. The parameters of the bright
objects, overexposed on the Schmidt plates, are taken from the Tycho-2
(I/259) catalog. The computed proper motions are not yet publically
available because of 10mas/year systematic errors discovered for the
southern hemisphere that are still under investigation.
Copyright:
The GSC-II is copyrighted (c) 2001-2005 by the Association of
Universities for Research in Astronomy, Inc.; see the copyright
notices from:
http://gsss.stsci.edu/Acknowledgements/DataCopyrights.htm
Scientists and educators who are using these data for research,
teaching purposes and other non-profit activities may freely use these
data and we only request that you acknowledge the source in any
publication (see the "Acknowledgements" section below).
Commercial use of these data is prohibited without permission.
Please contact STScI for further information regarding the different
copyright holders from
http://gsss.stsci.edu/Acknowledgements/DataCopyrights.htm
Release Notes and Limitation Notice: see
http://gsss.stsci.edu/catalogs/gsc/gsc2/gsc23/gsc23_release_notes.htm
See also:
http://gsss.stsci.edu/catalogs/gsc/gsc2/gsc2.htm : the GSC-II Home Page
I/254 : The HST Guide Star Catalog, Version 1.2 (Lasker+ 1996)
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
I/271 : The Guide Star Catalog, Version 2.2 (GSC2.2) (STScI, 2001)
File Summary:
FileName Lrecl Records Explanations
× 80 . This file
× ReadMe 80 . This file
× out.sam 205 100 Sample records of GSC2.3.2 (near 0+0)
Byte-by-byte Description of file: out.sam
Bytes Format Units Label Explanations
1- 10 A10 --- GSC2.3 [NS0-9A-Z] Identification of the object (1)
13- 22 A10 --- GSC1 Identification in GSC Version 1 (Cat. I/254)
25- 32 A8 --- HTM6 [NS0-3] HTM-6 designation as in GSC2.2 (1)
34- 43 F10.6 deg RAdeg Right Ascension (J2000), at "Epoch"
44- 53 F10.6 deg DEdeg Declination in (J2000), at "Epoch"
55- 59 F5.2 arcsec e_RAdeg Mean error on RAdeg (2)
61- 65 F5.2 arcsec e_DEdeg Mean error on DEdeg (2)
67- 74 F8.3 yr Epoch Epoch of the position
77- 81 F5.2 mag Fmag ? Magnitude in F photographic band (red)
84- 87 F4.2 mag e_Fmag ? Mean error on Fmag
89- 90 I2 --- n_Fmag ? Coded emulsion / bandpass / filter (2)
93- 97 F5.2 mag jmag ? Magnitude in Bj photographic band (blue)
100-103 F4.2 mag e_jmag ? Mean error on jmag
105-106 I2 --- n_jmag ? Coded emulsion / bandpass / filter (2)
109-113 F5.2 mag Vmag ? Magnitude in V photographic band (green)
116-119 F4.2 mag e_Vmag ? Mean error on Vmag
121-122 I2 --- n_Vmag ? Coded emulsion / bandpass / filter (2)
125-129 F5.2 mag Nmag ? Magnitude in N photographic band (0.8µm)
132-135 F4.2 mag e_Nmag ? Mean error on Nmag
137-138 I2 --- n_Nmag ? Coded emulsion / bandpass / filter (2)
141-145 F5.2 mag Umag ? Magnitude in U band (Johnson)
148-151 F4.2 mag e_Umag ? Mean error on Umag
153-154 I2 --- n_Umag ? Coded emulsion / bandpass / filter (2)
157-161 F5.2 mag Bmag ? Magnitude in B band (Johnson blue)
164-167 F4.2 mag e_Bmag ? Mean error on Bmag
169-170 I2 --- n_Bmag ? Coded emulsion / bandpass / filter (2)
174 I1 --- Class [0,5] Object class (3)
176-185 I10 --- Status Source status flag (4)
186 A1 --- M [M] 'M' for multiple object (5)
189-194 F6.2 pix a ? Semi-major axis of fitting ellipse
196-199 F4.2 --- e ? Eccentricity of fitting ellipse
201-205 F5.1 deg aPA ? Position angle (N->E) of fitting ellipse
Note (1): The GSC2.3 identification differs from GSC2.2.
Is is made of 10 characters, the first four representing the level-6
HTM (Hierarchical Triangular Mesh) coded in base 36 (0..9 and A..Z),
and the last 6 represent a zero-filled sequence number assigned to
each source upon initial detection.
The Hierarchical Triangular Mesh (HTM) is a recursive spatial indexing
scheme dividing the unit sphere into spherical triangles, the number
of triangles at level n being 8x4n (see details about HTM at
http://www.sdss.jhu.edu/htm/). The level-6 HTM varies from N000 to
NCN3 and S000 to SCN3, i.e. 16384*2 different regions.
The designation of the corresponding GSC2.2 object, if existing,
is made by replacing the 4 first digits of the GSC2.3 identifier
by the 8 HTM6 digits, and removing the leading zeroes of the number
made by digits 5-10 of the GSC2.3 identifier.
Note (2): coded emulsion / bandpass / filter:
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bcode Name Emulsion/Filter
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0 Jpg IIIaJ+GG395 (SERC-J/EJ)
1 V IIaD+W12 (Pal Quick-V)
2 - HST FGS
3 B (Johnson)
4 V (Johnson)
5 Fpg IIIaF+RG630 (ESO-R)
6 V495 IIaD+GG495 (Pal QV/AAO XV)
7 O 103aO+no filter (POSS-I Blue)
8 E 103aE+red plexi (POSS-I Red)
9 Fpg IIIaF+RG630
10 - IIaD+GG495+yellow objective (GPO Astrograph)
11 - 103aO+blue objective (Black Birch Astrograph)
12 - 103aO+blue objective Black Birch Astrograph, GSC cal.)
13 - 103aG+GG495+yellow objective (Black Birch Astrograph)
14 - 103aG+GG495+yellow objective (Black Birch Astrograph, GSC)
16 Vpg IIIaJ+GG49
18 Jpg IIIaJ+GG385 (POSS-II Blue)
19 U (Johnson)
20 R (Johnson)
21 I (Johnson)
22 U (Cape)
23 R (Kron)
24 I (Kron)
35 Fpg IIIaF+RG610 (POSS-II Red)
36 Fpg IIIaF+OG590 (SERC-ER/SR, AAO-R/GR)
37 Npg IVN+RG9 (POSS-II IR)
38 Npg IVN+RG715 (SERC-IR)
39 Jpg IIaO+GG385 (ESO-B)
41 BT TYCHO-B
42 VT TYCHO-V
43 - IRAS 12micron
44 - IRAS 25 micron
45 - IRAS 60 micron
46 - IRAS 100 micron
47 J (2MASS)
48 H (2MASS)
49 K (2MASS)
50 u' (SDSS)
51 g' (SDSS)
52 r' (SDSS)
53 i' (SDSS)
54 z' (SDSS)
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Note (3): the object class is defined as:
0=star 1=Galaxy, 2=Blend
3=Non-star 4=unclassified 5=Defect
In the version 2.3.2, only values 0 and 3 are present.
Note (4): the status code is a 10-digit field encoding the properties
of the catalog object. This flag is 99999900 for a Tycho object.
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........xx Number of plates on which the object appeared.
.......x.. Centroid type associated with the exported position, as:
0 = barycenter 4 = multicircular
1 = circular gaussian 5 = multielliptical
2 = elliptical gaussian 6 = FPA + circular
3 = FPA-applied barycenter 7 = FPA + elliptical
(FPA = Fractional Pixel Allocation)
......x... Quality of exported J magnitude, as:
0 = not present 1 = fit 2 = extrapolated
.....x.... Quality of exported F magnitude, as:
0 = not present 1 = fit 2 = extrapolated
....x..... Quality of exported V magnitude, as:
0 = not present 1 = fit 2 = extrapolated
...x...... Classification unanimity
0 = mixed vote 2 = unanimous defect
1 = unanimous vote
..x....... Classification voters
0 = several 15um scan 2 = several 25um scan
1 = one 15um scan 3 = one 25um scan
.x........ Processing status
0 = complete processing on all plates
1 = object too big (>2562 pix) on at least one plate
x......... Deblending
0 = single object on all plates
1 = child (deblended) object on at least one plate.
----------------------------------------------------------------------
Note (5): this flag concerns only the Tycho stars (Status=99999900)
Acknowledgements:
The Guide Star Catalogue-II is a joint project of the Space Telescope
Science Institute and the Osservatorio Astronomico di Torino. Space
Telescope Science Institute is operated by the Association of
Universities for Research in Astronomy, for the National Aeronautics
and Space Administration under contract NAS5-26555. The participation
of the Osservatorio Astronomico di Torino is supported by the Italian
Council for Research in Astronomy. Additional support is provided by
European Southern Observatory, Space Telescope European Coordinating
Facility, the International GEMINI project and the European Space
Agency Astrophysics Division.
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(End) Francois Ochsenbein [CDS] 19-Apr-2007