[vsnet-grb-info 7876] GRB 090520: GROND upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9420
SUBJECT: GRB 090520: GROND upper limits
DATE:    09/05/22 23:53:35 GMT
FROM:    Andrea Rossi at TLS Tautenburg  <rossi at tls-tautenburg.de>

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

GROND (Greiner et al. 2008, PASP 120, 405) at the 2.2m ESO/MPI telescope at La
 Silla Observatory (Chile) 
started follow-up observations of GRB 090520 (Cummings et al. 2009, GCN #9417)
 on May 21, at 09:35 UTC 
(~32 h after the burst). In addition, a second epoch of imaging was obtained,
 which started on May 22, 09:37 UTC.

Image subtraction does not reveal any variable source between the two epochs. 
The first epoch thus yields the following upper limits:

g > 23.8
r > 24.0
i > 23.4
z > 23.2
J > 21.8
H > 21.4
K > 20.8

obtained using the GROND zeropoints and 2MASS field stars as reference.