GCN Circular 12913
Subject
GRB 120202A: GROND observations
Event
Date
2012-02-03T23:59:46Z (14 years ago)
From
Patricia Schady at MPE/Swift <pschady@mpe.mpg.de>
P. Schady, J. Greiner (both MPE Garching), S. Schmidl and D.A. Kann
(both TLS Tautenburg), J. Greiner (MPE Garching) and report on behalf
of the GROND team:
We observed the field of the INTEGRAL burst GRB 120202A (Mereghetti et
al., GCN #12909) simultaneously in g'r'i'z'JHK with GROND (Greiner et
al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at La
Silla Observatory (Chile).
Observations started at 06:25 UT on February 3rd, 8.8 hrs after the
GRB trigger. They were performed at an average seeing of 1arcsec and
at high airmass.
Within a 1.5hrs of stacked data we detect a source within the Swift-
XRT error circle (Holland et al., GCN #12911) consistent with the
first position reported by Tanvir et al. (GCN #12912). We measure an
r'(AB) magnitude of 24.8+/-0.2, in agreement with Tanvir et al.
In addition, we also detect the second source reported by Tanvir et
al. in all the GROND optical and NIR bands, although we find that
during our observations the source faded by 0.2-0.3 magnitudes. At a
mid-time of 06:53 UT the source had an r'(AB) magnitude of 23.7+/-0.1,
and at a mid-time of 08:11UT had faded to 24.0+/-0.1.
The above magnitude has been calibrated against SDSS and is not
corrected for the expected Galactic foreground extinction
corresponding to a reddening of E_(B-V)=0.02 mag in the direction of
the burst (Schlegel et al. 1998).