TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4208
SUBJECT: GRB051103: optical observations
DATE:    05/11/07 23:53:33 GMT
FROM:    Eran Ofek at Tel Aviv U.  <eran@wise1.tau.ac.il>

E. O. Ofek, S. B. Cenko, A. M.  Soderberg, S. R. Kulkarni (Caltech), D. B.
Fox (Penn State) report on behalf of the Caltech-NRAO-Carnegie
Collaboration:

We have observed the entire error box of the IPN short hard burst GRB
051103 (Golenetskii et al. 2005, GCN 4197) using the Robotic Palomar
60-inch telescope.  We acquired 8 pointings (3-9 180sec R-band images
each) that cover the entire IPN error box over epochs between 2.96 and
3.16 days after the GRB trigger.

A comparison between the Palomar 60-inch image and POSS2 R-band image
did not reveal any new source brighter than limiting magnitude of about
R=19.5.  Our images are deeper than the POSS images, and there are
several possible fainter variable/defects sources within the error box.
Second epoch images are scheduled.

Assuming that the GRB is related with the M81/M82 group, and using a
distance modulus of 27.8 (Freedman et al. 1994), and A_R=0.2 Galactic
extinction (Schlegel et al. 1998), we can set an upper limit of -8.5
(comparable to the absolute magnitude of novae) on the R-band absolute
magnitude of an optical transient.