GCN Circular 9862
Subject
GRB 090831C: GROND upper limits
Event
Date
2009-09-01T18:45:16Z (16 years ago)
From
Thomas Kruehler at MPE/MPI <kruehler@mpe.mpg.de>
F. Olivares, T. Kruehler and J. Greiner (all MPE Garching) report on behalf
of the GROND team:
We observed the field of GRB 090831C (Swift trigger #361489; Schady et al.,
GCN #9854) 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 LaSilla
Observatory (Chile).
Observations started at 08:07 UT on September 1st, 2009, 10.6 hr after the
burst. At this time the position of the burst was becoming visible above
the pointing constraints of the telescope. Observations suffer from high
airmass and large seeing of around 2". In stacked images of 74 min total
integration time in griz and 60 min in JHK, we do not detect any object
within the enhanced XRT error circle (Evans et al., GCN #9855), down to the
following limiting magnitudes (all in the AB system):
g' > 23.5
r' > 24.0
i' > 23.3
z' > 22.9
J > 21.4
H > 21.1
K > 20.0
These upper limits were derived using the GROND zeropoints and 2MASS field
stars as reference and are not corrected for significant Galactic
foreground extinction corresponding to a reddening of E(B-V)=0.38 mag
(Schlegel et al., 1998).