[vsnet-grb-info 11151] GRB 111117A: NOT observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12563
SUBJECT: GRB 111117A: NOT observations
DATE:    11/11/17 22:57:59 GMT
FROM:    Antonio Deugarte at IAA-CSIC  <deugarte at iaa.es>

Michael I. Andersen (DARK), Antonio de Ugarte Postigo (IAA-CSIC and DARK),
Giorgos Leloudas (DARK), Johan P. U. Fynbo (DARK) report on behalf of a
larger collaboration:

Using ALFOSC on the Nordic Optical Telescope (NOT) we have obtained R-band
(6 x 300 s) imaging of the field of the Swift GRB 111117A (Mangano et
al., GCN 12559), starting on 2011 November 20:49:50 UT (mean epoch 7.88
hours after the burst trigger). The seeing during the observations was
around 0.9".

In a preliminary reduction we detect a source with a magnitude of R=23.1 +/- 0.3 
(based on USNO-B1.0 photometry) at the coordinates (J2000.0 +/- 1"):

R.A.: 00:50:46.28
Dec.: +23:00:40.3

This is formally 3.6" from the XRT position and thus outside the
XRTerror circle reported in GCN 12559. However we note that it is
within the automatically generated SPER error box
(http://www.swift.ac.uk/sper/507901/).
We therefore suggest that this object is the host galaxy or afterglow of
GRB 111117A.

We are grateful to the NOT observers, Kristian Vida (Konkoly Observatory) and
Heidi Korhonen (U. Copenhagen) for obtaining these observations.