TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2915
SUBJECT: GRB041226: ROTSE-III Optical Observations
DATE:    04/12/27 03:02:30 GMT
FROM:    Eli Rykoff at U of Michigan/ROTSE  <erykoff@umich.edu>

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

ROTSE-IIIb, located at McDonald Observatory, Texas, responded to Swift 
GRB041226 (GCN #2914).  An automatic response was initiated during early 
twilight hours.  The first usable image taken at 27 Dec. 00:46:47 UT, 
4.2 hours after the burst.  We took 300 20-s exposures.  All the images 
were taken with >99% moon illumination.  The unfiltered images were 
calibrated relative to USNO A2.0.  Individual images have limiting 
magnitudes improving from 15 to 16.8 as the sky darkened.  Comparison to 
DSS (second epoch) reveals no new sources within the 3-sigma error 
circle to a limiting magnitude of 16.1 for stacks of 10 images taken 4.2 
hours after the burst and 17.7 for stacks of 10 images taken 5 hours 
after the burst.