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GCN Circular 278

Subject
GRB 990316 optical observations
Date
1999-03-18T13:16:57Z (25 years ago)
From
James Rhoads at KPNO <rhoads@noao.edu>
Howard E. Bond (Space Telescope Science Institute), Kevin M. McLin (CASA,
University of Colorado), and James Rhoads (Kitt Peak National Observatory)
report on behalf of the KPNO GRB followup team:

We have observed the location of the LOTIS candidate optical transient
reported by Park et al (GCN 277).  Bond has obtained a 300 second V band
image using the KPNO 4 meter Mayall telescope; the observation is
centered at 1999 March 18, 06:45 UT.

McLin observed the same field for a total of 1800 seconds in R band using
the KPNO 0.9 meter telescope; the observations were centered at 06:30 UT.

Conditions were clear with 1.6 to 1.7 arcsecond seeing.

Comparing our images to the digitized POSS-II red plates, we find no
compelling evidence for any new source above the POSS plate limit.
This implies an approximate limit of R>21 for any fading source
consistent with the location of the LOTIS candidate.
(We have assumed that the positional uncertainty is less than 1 arcminute
for the LOTIS source, based on the 15 arcsecond LOTIS pixel size.  Our
actual fields of view were 36' for the 4m and 23' for the 0.9m data, so
could be used to search for transients over a larger area.)

Our R and V band images are both deeper than the POSS plates, and further
CCD photometry is encouraged to see whether any fainter sources are varying.
The R band image and a subsection of the V band image are available
on the Web from http://www.noao.edu/noao/grb/990316.html .  Please note
that these images are not fully reduced; they will be replaced with
fully reduced images when available.
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