TITLE:   GCN CIRCULAR
NUMBER:  19293
SUBJECT: GRB 160411A: Gemini-S optical observations
DATE:    16/04/11 18:34:24 GMT
FROM:    Andrew Levan at U.of Leicester  <A.J.Levan@warwick.ac.uk>

A.J.Levan (U. Warwick), W. Fong (Arizona) report on behalf of a larger collaboration:

“We observed the location of GRB 160411A (Page et al. GCN 19279, Evans et al. GCN 19283) with Gemini-S and GMOS starting at 09:35 UT on 2016 April 11. Observations were taken in the i-band and began 9 hours after the BAT trigger. They were taken at the start of morning twilight as the source was rising, because of this the seeing is poor (1.4”) and depth relatively shallow. 

The region around the enhanced XRT position is relatively complex, with multiple sources in the surrounding area. Two obvious sources are located just outside the Eastern and Western edge of the XRT circle at locations of

Source A: 
RA(J2000) 23:17:25.99
DEC(J2000) -40:14:32.0

Source B: 
RA(J2000) 23:17:25.37
DEC(J2000) -40:14:30.5

The sources have comparable magnitude and appear to be marginally extended, although the poor seeing and signal to noise complicates such analyses. 

With thank the Gemini staff, in particular Bryan Miller, for their assistance with these observations”