J/ApJ/446/115 Gamma ray burst localizations (Vrba+ 1995)
Deep optical counterpart searches of gamma-ray burst localizations
Vrba F.J., Hartmann D.H., Jennings M. C.
<Astrophys. J. 446, 115 (1995)>
=1995ApJ...446..115V 1995ApJ...446..115V
ADC_Keywords: QSOs ; Gamma rays
Keywords: gamma rays: bursts - quasars: general - surveys -
techniques: photometric
Abstract:
We report the results of a 5 year CCD imaging program of small
gamma-ray burst (GRB) error boxes from the First Interplanetary
Network and an optical transient field. The fields include GBS
0010-16, GBS 0552-08, GBS 1028+46, GBS 1205+23, GBS 1412+79, OTS
1809+31, GBS 2006-22, and GBS 2252-03. A total of 274 hours of open
shutter time was used to obtain multiple UBVI-filtered frames covering
an area approximately twice that of the 99% confidence localizations.
For 2070 objects in these fields above the survey detection limit of
V∼24, 79,000 calibrated photometric measurements were made. The
objectives of the survey were to search for objects of unusual colors,
variability, or proper motions. The final census of objects in these
fields is consistent with the expected numbers of normal stars,
galaxies, and proper motion objects based on statistics of large-scale
surveys. While no obvious GRB optical counterparts were found, several
potentially interesting objects were discovered, along with marginal
evidence for a QSO excess at the rate of one per high Galactic
latitude localization. The results and implications are discussed in
detail along with suggestions for future work.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 108 2074 Condensed Database
table6.dat 99 27 Objects of possible interest
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Field *Field name
13- 16 I4 --- Object *Object identification number
17 A1 --- Gal [g ] Indicates if object is a resolved galaxy
19- 24 F6.3 mag Vmag []?=-9.000 Mean V magnitude
26- 31 F6.3 mag e_Vmag *[]?=-1.000 Uncertainty in Vmag
33- 39 F7.3 mag B-V []?=-9.000 Mean (B-V) color
41- 46 F6.3 mag e_B-V *[]?=-1.000 Uncertainty in B-V
48- 54 F7.3 mag U-B []?=-9.000 Mean (U-B) color
56- 61 F6.3 mag e_U-B *[]?=-1.000 Uncertainty of U-B
63- 69 F7.3 mag V-I []?=-9.000 Mean (V-I) color
71- 76 F6.3 mag e_V-I *[]?=-1.000 Uncertainty in V-I
78- 84 F7.3 mag U-V []?=-9.000 Mean (U-V) color
86- 91 F6.3 mag e_U-V *[]?=-1.000 Uncertainty in U-V
93- 99 F7.2 pix Xpos *? X pixel coordinate
101-108 F8.2 pix Ypos *? Y pixel coordinate
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Note on Field:
Eight GBS or OTS fields are arranged in increasing order of Galactic
latitude. The field name is repeated here for each object.
Note on Object:
Object identification numbers for each field are arranged in
decreasing order of declination.
Note on e_Vmag, e_B-V, e_U-B, e_V-I, e_U-V:
The uncertainties listed are the larger of i) the weighted standard
deviation of the mean, or ii) the minimum error based on the
photometric uncertainties of individual observations. Thus, the
listed error represents the uncertainty of the value whether
primarily due to photometric error or variability. A -9.000 or
-1.000 in the color/magnitude and uncertainty columns, respectively,
indicates that there are insufficient data to calculate that
quantity. A few lines of data are listed to only .01mag
precision. These are highly extended objects whose photometric data
were obtained by synthetic aperture photometry, rather than the
usual point spread function fitting, as described in the text of the
printed paper.
Note on Xpos, Ypos:
The fiducial pixel coordinates (X,Y, with the origin at the
northeast corner of each field) for each object to the nearest .01
pixel. Most pixel coordinates are from the Daophot `find' routine
and have internal precisions of .01 pixel for the best exposed
objects to about 1.0 pixel for the faintest and/or extended
objects. Additionally, those objects with all zeros to the right of
the decimal point for both X and Y were added to the object list by
hand and have internal precisions of only 1.0 pixel. There was no
attempt to estimate the internal precisions for each object since,
as explained in Section 2.7 of the printed paper, the positional
errors are dominated by not knowing the CCD rotation to better than
about 0.5 degree. For an object lying 400 pixels from the center of
the field this amounts to a 3.5 pixel error. At the telescope scale
of 0.4295 arcsec/pixel the combined errors could be as large as 2
arcsec. Thus, the pixel coordinates should be used for
identification purposes only and not for high accuracy
astrometry. Finally, there are three objects (one each in the fields
OTS 1809+31, GBS 2006-22, GBS 1205+23) with blank fields in X and Y.
These are due to CCD artifacts which were realized as such only
until well after the final object numbering system was finalized.
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Field Field name (Gamma Burst Source)
13- 15 I3 --- No Object number
18 I1 --- o_Umag Number of observation in U filter
20 I1 --- o_Bmag Number of observation in B filter
22- 23 I2 --- o_Vmag Number of observation in V filter
25- 26 I2 --- o_Imag Number of observation in I filter
29- 33 F5.2 mag Vmag V magnitude
35- 37 F3.2 mag e_Vmag rms uncertainty on Vmag
40- 43 F4.2 mag B-V B-V colour index
45- 47 F3.2 mag e_B-V rms uncertainty on B-V
50- 54 F5.2 mag U-B ? U-B colour index
56- 58 F3.2 mag e_U-B ? rms uncertainty on U-B
61- 64 F4.2 mag V-I V-I colour index
66- 68 F3.2 mag e_V-I rms uncertainty on V-I
71- 73 A3 --- GRBBox This column answers whether the object lies
within the IPN 99% confidence localization (1)
74- 77 F4.2 arcmin Dist ? Approximate distance to the nearest edge of
the localization for objects that lies
outside the localization.
80- 99 A20 --- Com Comments (1)
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Note (1): NA = not associated; IPN: Cline et al., 1980ApJ...237L...1C 1980ApJ...237L...1C
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History:
* 07-Oct-1995: AAS CD-ROM series, Volume 5, 1995 (Lee Brotzman [ADS])
* 12-Nov-1996: table6 added at CDS.
(End) [CDS] 08-Jan-1997