[vsnet-grb-info 5020] GRB 070809: ROTSE-III Optical Limits
GCN Circulars
gcncirc at capella.gsfc.nasa.gov
Fri Aug 10 04:56:16 JST 2007
TITLE: GCN CIRCULAR
NUMBER: 6729
SUBJECT: GRB 070809: ROTSE-III Optical Limits
DATE: 07/08/09 19:56:11 GMT
FROM: Eli Rykoff at U of Michigan/ROTSE <erykoff at umich.edu>
E.S. Rykoff (U Mich), F. Yuan (U Mich), C. Akerlof (U Mich), H. Swan (U Mich),
B. E. Schaefer (Louisiana State), R. Quimby (U Texas), report on behalf of the
ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, responded
to GRB 070809 (Swift trigger 287344; Marshall, et al., GCN 6728), producing
images beginning 10.2 s after the GCN notice time. An automated response took
the first image at 19:22:48.2 UT, 30.9 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. Individual images have limiting magnitudes ranging
from 15.8-17.4; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
19:22:48.2 19:22:53.2 5 16.1 30.9 N
19:22:48.2 19:24:06.2 78 17.5 30.9 Y
19:24:19.9 19:29:06.8 286 18.1 122.6 Y
19:29:16.6 19:40:41.9 685 18.4 419.3 Y
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