GCN Circular 13393
Subject
GRB 120624B: GROND upper limits
Date
2012-06-28T09:14:58Z (13 years ago)
From
Patricia Schady at MPE/Swift <pschady@mpe.mpg.de>
P. Schady (MPE Garching), A. Nicuesa Guelbenzu, S. Klose, D. A. Kann
(TLS Tautenburg), M. Nardini (Universita' degli Studi Milano-Bicocca),
and J. Greiner (MPE Garching) report on behalf of the GROND team:
We observed the field of the bright GRB 120624B (Fermi/GBM trigger
362269436/120624933, Gruber et al., GCN 13377, 13383; Konus-Wind
detection, Golenetskii et al., GCN 13382; Swift trigger 525068,
Sakamoto et al., GCN 13384) simultaneously in g'r'i'z'JHK with GROND
(Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG/ESO
telescope at La Silla Observatory (Chile).
Observations started at 23:17 UT on 2012-06-25, about 23 hrs after the
GRB trigger and lasted for about 2 hrs. At the time of our
observations, the angular distance of the source position to the Moon
(last quarter) was just 10 degrees, significantly increasing the
background in our optical images.
In stacked images of the first 20min in the g'-band, of the first hour
in r', i' and z' and the whole 2 hr period of J, H and K
observations, we do not detect any new source at the position of the
NIR afterglow candidate (D'Avanzo et al., GCN 13391), nor within the
BAT error circle (Sakamoto et al., GCN 13384). The 3sigma limiting AB
magnitudes are as follows
g' > 23.3
r' > 24.0
i' > 23.5
z' > 23.4
J > 21.7
H > 21.1
K > 20.0
The galaxy close to the NIR afterglow candidate position mentioned in
D'Avanzo et al. (GCN 13391) is clearly detected in our J and H-band
images, with AB magnitudes J=20.9+/-0.2 and H=20.4+/-0.2.
The above limits are derived based on calibrating the optical and NIR
images against GROND zeropoints and 2MASS field stars respectively,
and are not corrected for the Galactic foreground extinction
corresponding to a reddening of E(B-V)=0.06 mag in the direction of
the burst (Schlegel et al. 1998).