GCN Circular 10149
Subject
GRB 091109B: ROTSE-III Optical Limits
Date
2009-11-09T22:25:08Z (14 years ago)
From
Brad Schaefer at LSU <schaefer@grb.phys.lsu.edu>
B. E. Schaefer (Louisiana State), E.S. Rykoff (UCSB), T. Guver (U
Arizona), H. Flewelling (IfA/Hawaii), S. B. Pandey (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 091109B (Swift trigger 375409; S. R. Oates et al., GCN
10148), producing images beginning 9.4 s after the GCN notice time. An
automated response took the first image at 21:49:24.5 UT, 21.6 s after the
burst, under excellent conditions. We took 10 5-sec, 10 20-sec and 10
60-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 or the XRT error circle, for both single
images and coadding into sets of 10; the field is not crowded. Individual
images have limiting magnitudes ranging from 15.9-17.0; we set the
following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
21:49:24.5 21:49:29.5 5 16.0 21.6 N
21:49:24.4 21:50:40.5 76 16.9 21.5 Y