GCN Circular 18598
Subject
GRB 151111A: GROND confirmation of the afterglow and photometric redshift estimate
Event
Date
2015-11-13T18:01:27Z (10 years ago)
From
Jan Bolmer at MPE/Garching <jan@bolmer.de>
J. Bolmer, J. Graham, F. Knust and J. Greiner (all MPE Garching) report:
We reobserved the field of GRB 151111A (Swift trigger 663074; Page et al., GCN 18578) simultaneously in g���r���i���z���JHK
with GROND (Greiner et al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at ESO La Silla Observatory (Chile).
Observations started at 05:31:33 UT on November 13, about 1.9 days after the GRB trigger.
The initially reported source at the coordinates of RA, Dec = 56.84483, -44.16201 (+/- 0.2���) (Graham et al. GCN 18585)
has clearly faded (e.g. in the r��� band from 22.19 +/- 0.04 to 22.68 +/- 0.05 mag) and we thus conclude that this source is the optical afterglow of GRB 151111A.
Furthermore, after correcting for the galactic foregorund E(B-V)=0.01 mag, and
fitting a powerlaw model to the 7-cannel GROND SED from the first night,
we derive a photometric redshift of z = 3.5 +/- 0.3, according to the g'-band dropout
with g'-r��� = 1.3 mag.