[vsnet-grb-info 7913] GRB 090531: GROND upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9456
SUBJECT: GRB 090531: GROND upper limits
DATE:    09/05/31 08:07:23 GMT
FROM:    Andrea Rossi at TLS Tautenburg  <rossi at tls-tautenburg.de>

A. Rossi (Tautenburg), F. Olivares, and J. Greiner (both MPE Garching)
report on behalf of the GROND team:

We observed the field of GRB 090531 (Swift trigger 353627, Stamatikos et al.,
GCN #9454) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m
MPI/ESO telescope at La Silla Observatory (Chile). Observations started on
31 May 2009 at 01:47 UT, 2 minutes after the burst and continued until
03:29 UT.

We do not find any new source within the BAT error circle. Image subtraction
between the first and last images of each band does not reveal any variable
source. The first image , consisting of 4.4 min exposure in g'r'i'z' and
4 min in JHK, yields the following upper limits (all AB):

g' > 22.6
r' > 22.8
i' > 22.4
z' > 22.0
J  > 21.5
H  > 20.9
K  > 20.2

which were obtained using the SDSS and 2MASS field stars as reference.