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I/305         The Guide Star Catalog, Version 2.3.2   (GSC2.3)  (STScI, 2006)

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
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: 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 Release Notes and Limitation Notice: see See also: : 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
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 in ICRS (J2000), at "Epoch" 44- 53 F10.6 deg DEdeg Declination in ICRS (J2000) 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 Rmag 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 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: ---------------------------------------------------------------------- bcode Name Emulsion/Filter ---------------------------------------------------------------------- 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) ---------------------------------------------------------------------- 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. ---------------------------------------------------------------------- ........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.
(End) Francois Ochsenbein [CDS] 19-Apr-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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