[vsnet-grb-info 3936] GRB061025: ROTSE-III Confirmation of Optical Counterpart

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5759
SUBJECT: GRB061025: ROTSE-III Confirmation of Optical Counterpart
DATE:    06/10/26 19:56:13 GMT
FROM:    Fang Yuan at ROTSE  <yuanfang at umich.edu>

F. Yuan (U Mich), E.S. Rykoff (U Mich) report on behalf of the ROTSE
collaboration: 

Further analysis of the early ROTSE-IIIc images (Rykoff, et al, GCN 
5752) reveals a faint, fading afterglow at the XRT position (Mineo, et 
al, GCN 5753) consistent with the position of the i-band candidate 
reported by Berger (GCN 5754).  This source was not detected in the 
original analysis because of source confusion with a nearby star, and 
because the afterglow is near our detection threshold.

In our initial 5 s image beginning at 18:36:46.6 UT, 44.7 s after the 
burst, the afterglow is at 15.6+/-0.2 mag calibrated relative to USNO 
B1.0 (R).  It decays with a power law index ~ -0.9 up to ~155 s after 
the burst when it is no longer detected.

start UT       end UT      t_exp(s)   mag      t_start-tGRB(s)  Coadd?
--------------------------------------------------------------------
18:36:46.6   18:36:51.6      5      15.6+/-0.2     44.7          N