Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 13811

GRB 120923A: GROND Upper limits
2012-09-24T03:01:34Z (12 years ago)
Sylvio Klose at TLS Tautenburg <>
F. Knust (MPE Garching), S. Klose, A. Nicuesa Guelbenzu (both TLS 
Tautenburg), and J. Greiner (MPE Garching) report on behalf of the GROND 

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).
Looking for U.S. government information and services? Visit