GCN Circular 3406
Subject
GRB 050509c: ROTSE-III Optical Limits
Date
2005-05-10T15:19:36Z (20 years ago)
From
Eli Rykoff at U of Michigan/ROTSE <erykoff@umich.edu>
E.S. Rykoff (U Mich), H. Swan (U Mich), R. Quimby (U Texas), T.A. McKay
(U Mich), report on behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 050509c (HETE trigger 3751), producing images beginning
6.4 s after the GCN notice time. An automated response took the first
image at 22:46:19.6 UT, 25.7 s after the burst, under excellent
conditions. We took 10 5-sec, 10 20-sec and 120 60-sec eposures. These
unfiltered images are calibrated relative to USNO A2.0 (R). The final
error box reported by Prigozhin et al. (GCN 3402) was entirely contained
within the ROTSE-IIIc field of view of the initial response.
Comparison to the DSS (second epoch) reveals no new sources within the
SXC/WFC error box reported in GCN 3402; however, we are limited as the
field is somewhat crowded. Individual images have limiting magnitudes
ranging from 15.8-17.1. In particular, we set a limit of magnitude 15.9
in a single 5 s exposure, starting 25.7 s after the burst. Coadding the
images into sets of 10 reveals no new sources down to limits of 17.0
(136 s effective length (t_end-t_start), beginning 25.7 s post-burst),
17.5 (295.4 s effective length, beginning 170.7 s post-burst), and 17.7
(695 s effective length, beginning 466.1 s post-burst).