TITLE:   GCN CIRCULAR
NUMBER:  2899
SUBJECT: GRB041223: ROTSE-III Optical Observations
DATE:    04/12/23 20:08:44 GMT
FROM:    Eli Rykoff at Univ. of Michigan/ROTSE  <erykoff@umich.edu>

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

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, 
responded to Swift GRB041223 (GCN #2898).  A manual response was 
initiated at 18:27 UT, around 4.5 hours after the burst.  We took 10 5-s 
exposures followed by 200 20-s exposures.  The first images were taken 
during twilight, and all the images were taken with >90% moon 
illumination.  The unfiltered images were calibrated relative to USNO 
A2.0.  Individual images had limiting magnitudes around 16.8. Comparison 
to DSS (second epoch) reveals no new sources within the 3-sigma error 
circle to a limiting magnitude of 18.4 for a stack of the first 90 images.