[vsnet-grb-info 5821] GRB 080320: ROTSE-III Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  7472
SUBJECT: GRB 080320: ROTSE-III Optical Limits
DATE:    08/03/20 05:01:51 GMT
FROM:    Fang Yuan at ROTSE  <yuanfang at umich.edu>

F. Yuan (U Mich), E.S. Rykoff (UCSB), W. Rujopakarn (Steward), report on 
behalf of the ROTSE collaboration:

ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 
080320 (Swift trigger 306858), producing images beginning 6.5 s after 
the GCN notice time. An automated response took the first image at 
04:38:10.5 UT, 32.1 s after the burst, under fair conditions. We took 10 
5-sec, 10 20-sec and 20 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 16.4-17.5; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
04:38:10.5   04:38:15.5         5     16.5           32.1       N
04:38:10.4   04:39:17.5        67     18.1           32.0       Y