[vsnet-grb-info 7623] GRB 090418B: GROND observations

GCN Circulars gcncirc at capella.gsfc.nasa.gov
Tue Apr 21 07:22:41 JST 2009


TITLE:   GCN CIRCULAR
NUMBER:  9178
SUBJECT: GRB 090418B: GROND observations
DATE:    09/04/20 22:22:31 GMT
FROM:    Jochen Greiner at MPI  <jcg at mpe.mpg.de>

P. Afonso (MPE), S. Klose (Tautenburg), T. Kruehler and J. Greiner (both
MPE Garching), 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) started follow-up observations of
GRB 090418B (Copete et al., GCN #9150) on April 19, at 03:00 UTC (18.0 h
after the burst). In addition, a second epoch of imaging was obtained,
which started on April 20, 04:05 UTC.

Similar to Guidorzi et al. (2009, GCN #9176) we do not detect any new object 
with respect to SDSS/2MASS inside the BAT error circle. Image subtraction 
between the two epochs does not reveal any obvious variable source. Upper 
limits from the first observation are as follows (all in the AB system):

g' > 23.8 mag
r' > 24.0 mag
i' > 23.2 mag
z' > 23.0 mag
J > 22.0 mag
H > 21.4 mag
K > 20.8 mag

Quoted upper limits have been derived using SDSS and 2MASS field stars as
reference.


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