GCN Circular 6393
Subject
GRB 070509: ROTSE-III Optical Limits
Date
2007-05-09T03:14:54Z (17 years ago)
From
Eli Rykoff at U of Michigan/ROTSE <erykoff@umich.edu>
E.S. Rykoff (U Mich), W. Rujopakarn (Steward), B. E. Schaefer (Louisiana
State), report on behalf of the ROTSE collaboration:
ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 070509 (Swift trigger 278903), producing images
beginning 7.4 s after the GCN notice time. An automated response took
the first image at 02:56:22.4 UT, 475.1 s after the burst, under fair
conditions. We took 10 5-sec, 10 20-sec and continuing 60-sec exposures.
These unfiltered images are calibrated relative to USNO A2.0 (R).
Comparison to the DSS (second epoch) reveals no new sources within the
3-sigma 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 15.2-16.2; we set the following specific limits.
start UT end UT t_exp(s) mlim t_start-tGRB(s) Coadd?
--------------------------------------------------------------------
02:56:22.4 02:56:27.4 5 15.3 475.1 N
02:56:22.4 02:57:39.6 77 16.6 475.1 Y
02:57:53.8 03:02:39.5 285 17.2 566.5 Y