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GCN Circular 7336

Subject
GRB 080229A: ROTSE-III Optical Limits
Date
2008-02-29T17:42:42Z (16 years ago)
From
Brad Schaefer at LSU <schaefer@grb.phys.lsu.edu>
B. E. Schaefer (Louisiana State) and E.S. Rykoff (UCSB), report on behalf
of the ROTSE collaboration:

ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to
GRB 080229A (Swift trigger 304379; Cannizzo et al. 2008, GCN 7335),
producing images beginning 9.8 s after the GCN notice time. An automated
response took the first image at 17:05:31.8 UT, 32.3 s after the burst,
and during the gamma-ray emission, under excellent conditions. We took 10
5-sec, 10 20-sec and 20 60-sec exposures, with continuing exposures now
ongoing. These unfiltered images are calibrated relative to USNO A2.0 (R).

Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle; the field is not crowded.  Unfortunately,
the XRT position is close to a star of moderate brightness, so the optical
transient could possibly be hidden by the light from this star.  We do not
see any indication that the image of the star is not that of the PSF, and
preliminary image subtractions do not reveal any extra sources.  
Individual images have limiting magnitudes ranging from 14.7-16.1; we set
the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
17:05:31.8   17:05:36.8         5     14.7           32.3       N
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