GCN Circular 13811
Subject
GRB 120923A: GROND Upper limits
Date
2012-09-24T03:01:34Z (12 years ago)
From
Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>
F. Knust (MPE Garching), S. Klose, A. Nicuesa Guelbenzu (both TLS
Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND
team:
We observed the field of GRB 120923A (Swift trigger 534402; Yershov et
al., GCN 13796) simultaneously in g'r'i'z'JHK with GROND (Greiner et al.
2008, PASP 120, 405) mounted at the 2.2 m MPG/ESO telescope at La Silla
Observatory (Chile).
Observations started at 00:10 UT on Sep 24, 19 hrs after the GRB trigger,
and are continuing. In a first 30 min exposure, at a mid time 00:35 UT, we
do not detect any source at the position of the NIR transient reported by
Levan et al. (GCN 13802) down to (AB mags, 3 sigma)
g' > 23.5,
r' > 23.7,
i' > 23.0,
z' > 23.0,
J > 21.0,
H > 20.4.
These uper limits are derived based on calibrating the images against
GROND zeropoints and 2MASS field stars and are not corrected for the
Galactic foreground extinction corresponding to a reddening of E_(B-V)=
0.15 mag in the direction of the burst (Schlegel et al. 1998).