GCN Circular 20132

Subject

GRB 161104A: GROND observations

Event

Date

2016-11-05T07:37:21Z (9 years ago)

From

Ana Nicuesa at TLS Tautenburg <ana@tls-tautenburg.de>

A. Nicuesa Guelbenzu, S. Schmidl (both TLS Tautenburg) and J. Greiner
(MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 161104A (Swift trigger 720568; Mingo et
al., GCN 20123Loading...
 
 ) simultaneously in g'r'i'z'JHK with GROND (Greiner et
al. 2008, PASP 120, 405) mounted at the 2.2m MPG telescope at the ESO
La Silla Observatory (Chile).

Observations started at 04:00 UT on 2016-11-05, 18 hours after the GRB
trigger. They were performed at an average seeing of 1" and at an
average airmass of 1.2.  Inside the enhanced 3.2" XRT position (GCN
20124Loading...
 
 , Goad et al.) we find a single source at coordinates:

Source A
RA (J2000.0) = 05:11:34.46
DEC (J2000.0) = -51:27:36.3
with an uncertainty of 0.5" in each coordinate.

At the border of the XRT error circle lie two more sources  at coordinates:

Source B
RA (J2000.0) = 05:11:34.31
DEC (J2000.0) = -51:27:33.6

Source C
RA (J2000.0) = 05:11:34.73
DEC (J2000.0) = -51:27:34.2

Their r'-band AB magnitudes are:

Source A
r' = 24.1 +- 0.1 mag,
Source B
r' = 24.3 +- 0.1 mag,
Source C
r' = 25.1 +- 0.3 mag,

For the moment no evidence for a fading of any of these objects can be
stated.

Given magnitudes are calibrated against GROND zeropoints and are not
corrected for the Galactic foreground extinction corresponding to a
reddening of E_(B-V) = 0.01 mag in the direction of the burst
(Schlafly & Finkbeiner 2011).

We thank Angela Hempel, La Silla, for performing the observations.