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GCN Circular 181

Subject
GRB 981226 optical observations
Date
1998-12-30T05:52:14Z (25 years ago)
From
James Rhoads at KPNO <rhoads@noao.edu>
James Rhoads (KPNO), Jerome A. Orosz (Penn State University),
John Lee (Yale University), and Keivan Stassun (U Wisconsin);
report on behalf of the KPNO GRB followup team:
 
We have observed the field of GRB 981226 on 1998 December 27.156 (J.
Lee observing), 28.100 (J. Lee observing), and 29.096 (K. Stassun
observing) using the 0.9m telescope and CCD Mosaic Camera at Kitt Peak
National Observatory.  Total integration times were 24, 24, and 40
minutes on the three nights.  Intermittent cloud on the first night
resulted in a comparatively shallow image, with limiting magnitude R ~
20.5.  Limiting magnitudes on the 2nd and 3rd nights were R ~ 21.
(These are very approximate estimates based on the USNO-A catalog
magnitude R=16.9 for the star at 23:29:29.3 -23:57:36 [J2000].)  The
full field of view is 1 degree, and so covers the entire BeppoSAX WFC
error region and more.
 
Sections of the reduced images are available in FITS format
at http://www.noao.edu/noao/grb/981226.html together with further details.
Preliminary analysis yields no new sources clearly above the detection
limits for the POSS plates, and no convincingly variable sources.  We
do not detect any object at the position of the J band transient reported
by Castro-Tirado et al.  The source reported by Galama et al (GCNC 172) is
apparent in all of our images and does not appear to vary more than 20%;
tighter limits will require deeper images.
 
In addition, J. Orosz observed the field on the same three nights using the
KPNO 2.1m telescope with R band (Dec 27, 28 UT) and I band (Dec 29 UT) filters.
The data cover part of the original BeppoSAX WFC error box.
These data are also available from the same web site.
 
Further analysis of both data sets is underway.
This report is citable.
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