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GCN Circular 8106

GRB080810 - optical observations
2008-08-16T21:42:53Z (16 years ago)
Christina Thoene at Niels Bohr Institute,DARK Cosmo Ctr <>
Christina C. Thoene (DARK/NBI), Antonio de Ugarte Postigo (ESO) and
Christine Liebig (ARI Heidelberg) report:

We observed the field of GRB 080810 (Page et al. GCN 8080) with the Danish
1.54m telescope on La Silla/Chile on August 15.40 UT and 16.31 UT (4.85
and 5.76 days after the burst onset). We detect the decaying afterglow at
preliminary R-band magnitudes of 22.8+/-0.3 and 23.2+/-0.5.

Using the R band and unfiltered magnitudes published in GCNs (Rykoff et
al. GCN 8084, Burenin et al. GCN 8088, de Ugarte Postigo et al. GCN 8089 &
8090, Okuma et al. GCN 8091, Kocka et al. GCN 8092, Guidorzi et al. GCN
8093 & 8099, Andreev et al. GCN 8094, Yoshida et al. GCN 8097, Galeev et
al. GCN 8098 & 8102, Rumyantsev et al. GCN 8105) together with the data of
our own observations we find that the light curve can be described by a
powerlaw of index alpha = 1.12 +/- 0.02 between 400s and 1 day after the
burst. After 1 day there is a flux excess that can be seen both in the
optical and X-ray light curves (explaining the flattening measured by
Galeev et al., GCN8098 and Guidorzi et al., GCN8099), after which the
light curve begins to decay more steeply with an index in the optical of
alpha = 1.8 +/- 0.3.

Hail, thunderstorm and heavy rain currently prevent further observations
from the DK 1.54m.

C. Thoene and C. Liebig acknowledge the excellent cheese fondue at the
Swiss telescope yesterday evening.
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