GCN Circular 7633
Subject
GRB 080420A: ROTSE-III Optical Limits on a possible short burst
Date
2008-04-20T04:50:49Z (17 years ago)
From
Brad Schaefer at LSU <schaefer@grb.phys.lsu.edu>
B. E. Schaefer (Louisiana State), F. Yuan (U Mich), W. Rujopakarn
(Steward), report on behalf of the ROTSE collaboration:
ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB
080420 (Swift trigger 309665; Vetere, L. et al., GCN 7632) a possible
short burst, producing images beginning 8.1 s after the GCN notice time.
An automated response took the first image at 04:13:10.2 UT, 23.0 s after
the burst, under fair conditions. These observations were affected by the
Full Moon 75 degrees away. We took 10 5-sec, and 60 20-sec exposures.
These unfiltered images are calibrated relative to USNO A2.0 (R). Imaging
is on going.
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma Swift/BAT error circle; the field is not crowded. Individual
images have limiting magnitudes ranging from 16.1-17.1; we set the
following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
04:13:10.2 04:13:15.2 5 16.1 23.0 N
04:13:10.2 04:14:17.3 67 18.1 23.0 Y
04:24:09.3 04:28:51.6 282 18.5 682.1 Y