TITLE:   GCN CIRCULAR
NUMBER:  10842
SUBJECT: GRB 100615A: NTT/Ultracam imaging
DATE:    10/06/15 04:14:30 GMT
FROM:    Nial Tanvir at IofA U.Cambridge  <nrt@ast.cam.ac.uk>

V. Dhillon (U. Sheffield), R. Mignani (MSSL), S. Schulze (U. Iceland),
A. J. Levan (U. Warwick), N. R. Tanvir (U. Leicester), A. de Cia (U. 
Iceland) report on behalf of the ULTRACAM collaboration:

We observed the field of GRB 100615A (D'Elia et al., GCN 10841) with 
ULTRACAM (Dhillon et al., MNRAS, 2007, 378, 825) mounted on the 3.5-m NTT 
telescope on La Silla, beginning approximately 17 mins post-burst.

Stacking the images from 02:16:27 to 02:39:29 UT did not reveal any new
source down to 24 mag (3 sigma) in the i' band.

The deep limiting magnitude at early times, coupled with bright X-ray
afterglow with moderate hydrogen column density (D'Elia et al. GCN 10841)
is suggestive of a highly extinguished burst.