GCN Circular 822
Subject
GRB000911: optical VLT observations
Event
Date
2000-09-30T15:52:41Z (25 years ago)
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."