[vsnet-grb-info 5450] GRB 071122: ROTSE-III Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7122
SUBJECT: GRB 071122: ROTSE-III Optical Limits 
DATE:    07/11/22 02:00:31 GMT
FROM:    Eli Rykoff at UCSB  <erykoff at physics.ucsb.edu>

E.S. Rykoff (UCSB), W. Rujopakarn (Steward), B. E. Schaefer (Louisiana 
State), T.A. McKay (U Mich), H. Swan (U Mich), report on behalf of the 
ROTSE collaboration:

ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 
071122 (Swift trigger 297114; Stamatikos et al., GCN 7121), producing 
images beginning 8.5 s after the GCN notice time. An automated response 
took the first image at 01:24:51.5 UT, 85.9 s after the burst, under 
fair conditions. These observations were affected by proximity to the 
full moon. We took 10 5-sec, and 30 20-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 15.7-16.8; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
01:24:51.5   01:24:56.5         5     15.8           85.9       N
01:24:51.4   01:25:58.5        67     17.3           85.8       Y
01:26:12.0   01:30:54.8       282     17.8          166.4       Y