TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  3917
SUBJECT: GRB 050904: TAROT optical measurements
DATE:    05/09/04 22:18:42 GMT
FROM:    Alain Klotz at CESR-CNRS  <Alain.Klotz@free.fr>

Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:

We did not explore the location of the Haislip
et al. (GCNC 3913) source candidate in the first
analyzis reported in GCNC 3911. This source is
detected in three composited images taken by TAROT
in the 8 first minutes after GRB. Magnitudes are
calculated using the R USNO-B magnitudes of three
nearby stars.

[sec after GRB]
start      end    magnitude
    86      144    R>18.1 +/- 0.3 (no detected)
   150      253    R=18.5 +/- 0.3
   312      370    R=18.7 +/- 0.3
   376      479    R=19.1 +/- 0.4

Corresponding images can be seen at:
http://www.cesr.fr/~klotz/grb050904

After 8 minutes, the CCD camera cooler failed.
Then, images are very noisy. We will try to
obtain corresponding dark frames in the next
days to reprocess images after t_GRB+8 min.

This message can be cited.