TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  1615
SUBJECT: GRB 021004: Optical measurement at OHP
DATE:    02/10/10 07:32:26 GMT
FROM:    Michel Boer at CESR-CNRS  <Michel.Boer@cesr.fr>

A. Klotz and M. Boer CESR/CNRS (Toulouse, France), and W. Thuillot
IMCCE/BDL Paris, France report the following data on GRB 021004 obtained
with the 1.20 meter telescope at the OHP/CNRS (Observatoire de Haute
Provence - France).

Images were R-cousin filtered. Each measurement image results of
co-addition of 4 frames of 40s (dark and flat corrected). Magnitudes are
computed compared to the USNO star at 00:26:58.713 +18:56:56.61 (Fox et
al. GCN 1564) assuming R=15.64.

Magnitudes of GRB021004 : (R band) 

2002 oct. 04 22:04:44.5 UT (JD=2452552.41996) : 18.29
2002 oct. 04 22:12:01.7 UT (JD=2452552.42502) : 18.37
2002 oct. 04 22:20:32.3 UT (JD=2452552.43093) : 18.40
2002 oct. 04 23:51:04.3 UT (JD=2452552.49380) : 18.67
2002 oct. 04 23:57:13.2 UT (JD=2452552.49807) : 18.65

Dates are middle of exposures. This data fill nicely a gap around T0 +
0.4 when the decay index of the light curve increases.