[vsnet-grb-info 7149] GRB 081226: ROTSE-III Optical Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8730
SUBJECT: GRB 081226: ROTSE-III Optical Limits 
DATE:    08/12/26 01:32:34 GMT
FROM:    Brad Schaefer at LSU  <schaefer at grb.phys.lsu.edu>

B. E. Schaefer (Louisiana State), E.S. Rykoff (UCSB), F. Yuan (U Mich), 
report on behalf of the ROTSE collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia,
responded to GRB 081226 (Swift trigger 338177; Godet, GCN 8729), producing
images beginning 8.8 s after the GCN notice time. An automated response
took the first image at 01:04:02.8 UT, 25.4 s after the burst, under
excellent conditions. We took 10 5-sec, 20 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; the field is not crowded. Individual 
images have limiting magnitudes ranging from 16.8-17.4; we set the 
following specific limits.

start UT       end UT      t_exp(s)   mlim   t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
01:04:02.8   01:04:07.8         5     17.0           25.4       N
01:04:02.9   01:05:19.0        76     17.8           25.5       Y