[vsnet-grb-info 2011] GRB 050822: ROTSE-III Prompt Optical Limits

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3850
SUBJECT: GRB 050822: ROTSE-III Prompt Optical Limits
DATE:    05/08/22 04:43:28 GMT
FROM:    Eli Rykoff at U of Michigan/ROTSE  <erykoff at umich.edu>

E.S. Rykoff (U Mich) reports on behalf of the ROTSE collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, 
responded to GRB 050822 (Swift trigger 151486), producing images 
beginning 5.8 s after the GCN notice time. An automated response took 
the first image at 03:50:00.8 UT, 31.7 s after the start of the burst, 
and during the gamma-ray emission (GCN 3849).  These observations were 
affected by proximity to the full moon as well as early twilight. We 
took 10 5-sec, and 70 20-sec eposures. 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 at the XRT position, for both single images 
and coadding into sets of 10. Individual images have limiting magnitudes 
ranging from 15.0-16.2; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
03:50:00.8    3:50:05.8         5     15.1           31.7       N
03:50:00.8    3:51:24.8        84     16.6           31.7       Y
03:51:25.5    3:56:12.0       286     17.5          412.6       Y