GCN Circular 11091
Subject
GRB 100814A: GROND Detection of the Optical/NIR Afterglow
Event
Date
2010-08-14T11:20:51Z (16 years ago)
From
Patricia Schady at MPE/Swift <pschady@mpe.mpg.de>
R. Filgas, P. Schady and J. Greiner (MPE Garching) report on behalf of
the GROND team:
We observed the field of GRB 100814A (Swift trigger 431605; Beardmore
et al., GCN #11087) simultaneously in g'r'i'z'JHK with GROND (Greiner
et al. 2008, PASP 120, 405) mounted at the 2.2 m MPI/ESO telescope at
La Silla Observatory (Chile).
Observations started at 03:57 UT, 7 minutes after the GRB trigger at
03:50 UT, and are continuing. They were performed at an average seeing
of 1.2" and at an average airmass of 2.
We detect a single point source in all GROND optical (g'r'i'z') and
NIR bands (JHK) at a position consistent with the coordinates provided
by Schaefer et al. (GCN #11086) and Gronwall et al. (GCN #11088), and
consistent with the spectroscopic redshift of z=1.44 (O'Meara et al.
GCN #11089).
The afterglow decays as a power law with a best-fit index of alpha ~
0.5, decaying from r' = 18.0 +/- 0.1 at T+25 minutes down to r' = 19.5
+/- 0.1 (all in AB system) by the end of our observations, at T+6
hours. Analysis is on going.
Given magnitudes are calibrated against USNO zeropoints and are not
corrected for the expected Galactic foreground extinction
corresponding to a reddening of E(B-V)=0.02 in the direction of the
burst (Schlegel et al. 1998).