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GCN Circular 14031

GRB 121201A: GROND afterglow observations and photometric redshift
2012-12-02T04:20:52Z (12 years ago)
Thomas Kruehler at Dark Cosmology Center <>
T. Kruehler (DARK/NBI), S. Klose (TLS Tautenburg) and J. Greiner (MPE Garching) 
report on behalf of the GROND team:

We observed the field of the Swift GRB 121201A (Yershov et al., GCN 14025) 
simultaneously in g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) 
mounted at the 2.2m MPI/ESO telescope at La Silla Observatory (Chile).

Observations started on December 02, 2012, 00:28 UT which is roughly
12.0 hr after the trigger. We clearly detect the afterglow of 
GRB 121201A (Yershov et al., GCN 14025) in the optical filters, 
but not in the NIR bands. Based on stacked images at
a mid-time of 01:05 UT with an effective integration time of 25 min
in g'r'i'z' and 20 min in JHKs, we estimate preliminary AB magnitudes and 
upper limits of:

g' = 24.2 +- 0.2 
r' = 23.0 +- 0.1
i' = 22.7 +- 0.1
z' = 22.5 +- 0.1
J > 21.5
H > 21.0
Ks > 19.9

These magnitudes and upper limits are calibrated against SDSS standards 
in the optical, and 2MASS field stars in the NIR bands. After correcting 
for the Galactic extinction corresponding to a reddening of E(B-V)=0.01
(Schlegel et al. 1998),  a fit to this SED returns a photometric redshift of 3.6 +0.2 -0.3.
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