TITLE:   GCN CIRCULAR
NUMBER:  6951
SUBJECT: GRB 071020: ROTSE-III Analysis of Optical Counterpart
DATE:    07/10/20 08:07:20 GMT
FROM:    Fang Yuan at ROTSE  <yuanfang@umich.edu>

F. Yuan (U Mich), E.S. Rykoff (UCSB), T.A. McKay (U Mich), B. E. 
Schaefer (Louisiana State), R. Quimby (Caltech), H. Swan (U Mich), 
report on behalf of the ROTSE collaboration:

ROTSE-IIIb, located at McDonald Observatory, Texas, responded to GRB 
071020 (Swift trigger 294835; Holland, et al., GCN6949) and detected the 
optical counterpart (Schaefer, et al., GCN 6948). During our first 80 
seconds observation (starting 25.6 sec after the burst), the OT faded 
with a decay index of 1.52 +/- 0.03.

We notice that the burst location is 9.7h^-1 kpc from the central bulge 
of SDSS J075843.38+325141.7, a galaxy with an old stellar population 
located at z=0.0166. DR6 SDSS data suggest this galaxy as M_r ~ -19.4, 
and a central velocity dispersion of 135 km/s.