GCN Circular 9408
Subject
GRB 090519: GROND observation
Date
2009-05-20T08:02:04Z (16 years ago)
From
Jochen Greiner at MPI <jcg@mpe.mpg.de>
A. Rossi (Tautenburg), T. Kruehler, J. Greiner and A. Yoldas (all MPE Garching)
report on behalf of the GROND team:
We observed the field of GRB 090519 (Swift trigger 352648, M. Perri et al.,
GCN #9400) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m
ESO/MPI telescope at La Silla Observatory (Chile). Observations started on
19 May 2009 at 23:44 UT, 2.5 h after the burst, under challenging sky
conditions with cirrus.
We detect the afterglow at a position consistent with the enhanced XRT error
circle and NOT (Thoene et al., GCN #9403). With an exposure time of 40min in
JHK and 49min in griz, preliminary photometry yields the following AB
magnitudes:
g =25.0 +-0.4
r =23.5 +-0.2
i =23.5 +-0.3
z >23.6
J >21.9
H >20.7
K >19.9
calibrated using SDSS and 2MASS field stars. The quoted magnitudes are not
corrected for the galactic foreground extinction corresponding to a
reddening of E_(B-V)=0.04.
The large g-i color as compared to r-i indicates that the Lyman break may
be located in the g' band. Fitting the SED with Hyper-Z results in a
preliminary photometric redshift of z = 3.9+0.4-0.7, assuming no intrinsic
extinction.