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J/ApJ/491/93        JHK photometry of 9 gamma-ray burst fields (Larson+ 1997)

Extragalactic content of gamma-ray burst localizations Larson S.B., McLean I.S. <Astrophys. J. 491, 93 (1997)> =1997ApJ...491...93L
ADC_Keywords: Galaxies, photometry ; Gamma rays ; Photometry, infrared Keywords: galaxies: photometry - gamma-ray: bursts - infrared: galaxies - surveys Abstract: Results of a deep, near-infrared survey of a predetermined, consistent sample of gamma-ray burst localizations are presented. This systematic study, conducted from 1994 to 1996, is the first to be designed specifically to examine the extragalactic content of these regions of sky. JHK images of nine of the smallest error boxes from the third Interplanetary Network together with 70arcmin2 of control fields were obtained reaching levels up to 200 times fainter than those reached by previous infrared studies of burst locations. Photometric measurements and star/galaxy separation measurements of more than 3000 detected objects were made. An overabundance of brighter galaxies exists in the gamma-ray burst images at the 98% confidence level, which indicates that the bursts are cosmological. Both the level of this enhancement and the galaxy brightness, where it appears, match what is expected for host galaxies. As a group, the brightest galaxy within each error box is slightly brighter than normal but is still consistent with a random population of galaxies. Their positions within the boxes are also consistent with a random distribution, with no preference toward the center. The bright galaxy excess in these regions of sky, combined with a seemingly random population of brightest error box galaxies, suggest that either the true host galaxies are fainter or the error boxes do not point accurately to the hosts. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file grbcat.dat 72 1892 Catalogue of sources in 9 γ-ray burst fields
See also: IX/20 : The Fourth BATSE Burst Catalog (Paciesas+ 1998) Byte-by-byte Description of file: grbcat.dat
Bytes Format Units Label Explanations
1- 6 I6 --- GRB GRB field (name of the GRB) 8- 10 I3 --- No Object number in GRB field 12- 15 I4 pix Xpos X coordinate 17- 19 I3 pix Ypos Y coordinate 21- 28 F8.4 deg RAdeg Right ascension (J2000) (1) 30- 37 F8.4 deg DEdeg Declination (J2000) (1) 39- 43 F5.2 mag Jmag ? J (1.25 micron) magnitude of the object (2) 45- 48 F4.2 mag e_Jmag ? 1-sigma error in the J magnitude (3) 50- 54 F5.2 mag Hmag ? H (1.65 micron) magnitude of the object (2) 56- 59 F4.2 mag e_Hmag ? 1-sigma error in Hmag 61- 65 F5.2 mag K'mag Either the K' (2.11 micron) or Ks (2.16 micron) magnitude of the object (2) (4) 67- 70 F4.2 mag e_K'mag ? 1-sigma error in K' or Ks 72 A1 --- S/G [SG] Identifies whether the object has been classified as a star (S) or a galaxy (G)
Note (1): The right ascension and declination (J2000) of the object using the pixel coordinates and a minimal astrometry model. These coordinates should be accurate to better than 1 arcsec. Note (2): Empty magnitude cells mean that no photometric information is available. Magnitudes equal to 0 mean that the object is saturated. Note (3): 1 sigma error, derived by adding the zeropoint and statistical errors in quadrature. Note (4): Fields GRB 910219, 920325, 920711, 920720, and 920723 are K' magnitudes. The others are Ks magnitudes
Acknowledgements: Samuel B. Larson
(End) Patricia Bauer [CDS] 13-Feb-1998
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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