[vsnet-grb-info 7538] GRB 090404: GROND upper limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  9096
SUBJECT: GRB 090404: GROND upper limits
DATE:    09/04/06 13:03:26 GMT
FROM:    Jochen Greiner at MPI  <jcg at mpe.mpg.de>

P. Afonso, T. Kruehler, J. Greiner (MPE Garching) and S. Klose 
(TLS Tautenburg), report on behalf of the GROND team:

GROND (Greiner et al. 2008, PASP 120, 405), mounted at the 2.2m ESO/MPI
telescope at La Silla Observatory (Chile), observed the field of GRB 090404 
(H. Ziaeepour et al. 2009, GCN #9086) simultaneously in the g'r'i'z'JHK bands.
Observations started on April 5, at 06:19 UTC (14.4 h after the burst) and
were carried out at air mass higher than 2.2.

We obtained several short exposures with a total integration time of 80 min
in g'r'i'z' and 72 min in JHK.

We do not detect any new object in the stacked images inside the enhanced XRT 
error circle (Beardmore et al. 2009, GCN #9088), down  to the following 
limiting magnitudes (all in the AB system):
  
g' > 23.8
r' > 24.3
i' > 23.3
z' > 23.1
J  > 22.3 
H  > 21.6 
K  > 20.3 
  
The upper limits have been obtained using SDSS and 2MASS field stars as 
reference. No correction has been made for the expected extinction 
corresponding to E(B-V) of 0.02 mag.

We further note that the nearby object reported by D. Malesani et al. (2009, 
GCN #9093) is present in the SDSS catalog, and also detected with GROND at
very similar magnitudes.