TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  822
SUBJECT: GRB000911: optical VLT observations
DATE:    00/09/30 15:52:41 GMT
FROM:    Davide Lazzati at Osservatorio Astronomico di Brera  <lazzati@merate.mi.astro.it>

D. Lazzati, S. Covino, D. Fugazza, G. Ghisellini (Oss. Astr. 
Brera) report:

"We have obtained Bessel B, V, R and I band observations, using 
the FORS1 instrument at the VLT-UT1:

The radio/optical candidate (Berger et al., GCN 795; Price et 
al., GCN 796; see also GCN 798 and 799) is clearly detected in 
all our images with the following magnitudes:

Date 2000 UT      Exp.(s)  Filter  Magnitude 

Sept 28.224	  2600     B       24.9 +/- 0.1
Sept 28.255       1500     V       24.6 +/- 0.1
Sept 28.273	   900     R       24.23 +/- 0.15
Sept 28.284       1500     I       23.6 +/- 0.15

The photometry (still to be considered preliminar) has been 
performed relative to the stars reported by Henden (GCN 800).

Comparison of the measured R and I magnitudes with the measurements
reported by Price et al. (GCN 796) and Pedersen et al. (GCN 815)
give a time decay index:

	delta_R=1.5 +/- 0.14
	delta_I=1.6 +/- 0.35

fully consistent with each other.

BVRI spectrum, images and fit informations can be found at 
http://www.merate.mi.astro.it/~lazzati/GRB000911/

We thank the ESO VLT-UT1 service observing team.

This message is citable."