GCN Circular 6021
Subject
GRB 070110: optical break
Date
2007-01-22T20:20:04Z (17 years ago)
From
Daniele Malesani at Niels Bohr Inst,Dark Cosmology Center <malesani@astro.ku.dk>
D. Malesani, J.P.U. Fynbo (NBI/Dark), A.O. Jaunsen (Univ. Oslo), and
P.M. Vreeswijk (ESO), report on behalf of a larger collaboration:
We observed the optical afterglow of GRB 070110 (Krimm et al., GCN 6005)
with the ESO VLT + FORS1. BVRI photometry was secured around Jan 21.05
UT (~10.7 days after the GRB).
Afterglow photometry in the V band shows its magnitude to be V ~ 24,
significantly fainter than expected based on the extrapolation of the
UVOT decay, which would predict V ~ 22.5 (Krimm et al., GCN 6019; see
also GCN report 26.3). We also measure the relative decay in the R band
based on comparison with our previous images (Jaunsen et al., GCN 6010;
Malesani et al., GCN 6015), and find it steeper than the value reported
by UVOT in the U, B and V bands.
The above evidence supports a steepening of the optical light curve of
GRB 070110, which possibly occurred some 5 days after the GRB, the time
at which the UVOT light curves end.
Further observations are encouraged. We acknowledge excellent support
from the observing staff at Paranal.