GCN Circular 9102
Subject
GRB 090407: ROTSE-III Optical Limits
Date
2009-04-07T11:06:47Z (15 years ago)
From
Brad Schaefer at LSU <schaefer@grb.phys.lsu.edu>
B. E. Schaefer (Louisiana State), F. Yuan (U Mich), report on behalf of
the ROTSE collaboration:
ROTSE-IIIa, located at Siding Spring Observatory, Australia, responded to
GRB 090407 (Swift trigger 348650; H. Ziaeepour et al., GCN 9101),
producing images beginning 8.8 s after the GCN notice time. An automated
response took the first image at 10:29:05.8 UT, 40.2 s after the burst,
and during the gamma-ray emission, under fair conditions. We took 10
5-sec, 10 20-sec and 33 60-sec exposures. These unfiltered images are
calibrated relative to USNO A2.0 (R). Imaging is on going but the
source is getting low.
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 13.9-15.5; we set the
following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
10:29:05.8 10:29:10.8 5 14.1 40.2 N
10:29:05.8 10:31:19.0 133 16.1 40.2 Y