[vsnet-grb-info 6952] GRB 081121: ROTSE-III Detection of Optical Counterpart

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8536
SUBJECT: GRB 081121: ROTSE-III Detection of Optical Counterpart
DATE:    08/11/21 20:41:23 GMT
FROM:    Fang Yuan at ROTSE  <yuanfang at umich.edu>

F. Yuan (U Mich), W. Rujopakarn (Steward) report on behalf of the ROTSE 
collaboration:

ROTSE-IIIc, located at the H.E.S.S. site at Mt. Gamsberg, Namibia, 
responded to GRB 081121 (Swift trigger 335105). The first image was at 
20:36:30.0 UT, 57.2 s after the burst (8.9 s after the GCN notice time). 
The unfiltered images are calibrated relative to USNO A2.0. We detect a 
11.6 magnitude, fading source with coordinates:

     05:57:06.1      -60:36:10.3    (J2000), with positional uncertainty 
of 1" or better

start UT    	mag     mlim(of image)
----------------------------------
20:36:29.9     11.6     15.7 


This source is not visible in DSS (second epoch), 2MASS or the MPChecker 
database.

A jpeg image is available at 
http://www.rotse.net/images/gsb335105_3c00_img.jpg Note that the object 
marked 4 is the candidate in question.

Continuing observations are in progress.