[vsnet-grb-info 6804] GRB 081024A: ROTSE-III Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8399
SUBJECT: GRB 081024A: ROTSE-III Optical Limits
DATE:    08/10/24 06:33:52 GMT
FROM:    Brad Schaefer at LSU  <schaefer at grb.phys.lsu.edu>

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

ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 
081024A (Swift trigger 332516; G. Stratta, GCN 8398), producing images 
beginning 9.1 s after the GCN notice time. An automated response took the 
first image at 05:53:37.2 UT, 28.4 s after the burst, under excellent 
conditions. We took 10 5-sec, 10 20-sec and 40 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; however, we are limited as the field 
is somewhat crowded. Individual images have limiting magnitudes ranging 
from 16.1-17.1; we set the following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
05:53:37.1   05:53:42.1         5     16.2           28.3       N
05:54:57.0   05:59:37.7       280     17.2          108.2       Y