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GCN Circular 12622

GRB 111204A: GROND Observations
2011-12-05T08:13:42Z (12 years ago)
Alexander Kann at TLS Tautenburg <>
D. A. Kann (Tautenburg Observatory), F. Olivares E., and J. Greiner,
(both MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 111204A (Swift trigger 509018; Sonbas et
al., GCN #12612) simultaneously in g'r'i'z'JHK with GROND (Greiner et
al. 2008, PASP, 120, 405) mounted at the 2.2 m ESO/MPI telescope at La
Silla Observatory (Chile). Observations started on December 5, 2011,
at 00:38 UT, 11 hours after the GRB trigger, during twilight. They were
performed at an average seeing of 1".1 and at an airmass of 1.2 - 2.2.

Based on co-added images of 5900 s integration time in g'r'i'z' and
4800 s in JHK, centered 0.5253 days after the trigger, no new sources
within the enhanced 1".9 XRT error circle (RA = 22:26:30.81, Dec. =
-31:22:29.3; Beardmore et al., GCN #12614, updated version from the
Enhanced XRT Position page) are detected, and the following specific upper
limits (all in the AB magnitude system) are found:

g' > 24.5
r' > 24.9
i' > 24.4
z' > 24.0
J > 22.3
H > 21.6
K > 20.5

Magnitudes were calibrated against GROND zeropoints in g'r'i'z' and 2MASS
field stars in JHK. No corrections for the expected Galactic foreground
extinction were made, which correspond to a reddening of E(B-V)=0.012 mag
in the direction of the burst (Schlegel et al. 1998).
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