GCN Circular 10676
Subject
GRB 100424A: GROND Upper Limits
Date
2010-04-25T06:32:41Z (14 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 100424A (Swift trigger 420367; Hoversten et
al., GCN 10667) 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 00:16 UT on April 25, 7.7 hours after the GRB
trigger, and continued for 3 hours. The observations were severely
affected by passing cirrus clouds.
In our first stacked images of 24 min total integration time in g'r'i'z'
and 20 min in JHK, we do not (see also Malesani et al., GCN 10671, Levan
et al., GCN 10672, Morgan & Bloom GCN 10675) detect a source within the
enhanced Swift/XRT error circle (Evans et al., GCN 10669) down to the
following preliminary 3 sigma limiting magnitudes (all in the AB system):
g' > 23.03
r' > 23.37
i' > 22.96
z' > 23.04
J > 21.77
H > 21.21
K > 20.29
Later images do not increase these limiting magnitudes due to worse sky
conditions. These limits were derived by calibrating the images against
SDSS/2MASS field stars and are not corrected for the Galactic foreground
extinction corresponding to a reddening of E_(B-V)= 0.03 in the
direction of the burst (Schlegel et al. 1998).