GCN Circular 6532

A. Stefanescu (1), A. Slowikowska (2)(3), G. Kanbach (1), S. Duscha (1),
F. Schrey (1), H. Steinle (1), Z. Ioannou (4) of the OPTIMA-Burst Team
report the following:
(1)=MPE, Garching, (2)=FORTH, Heraklion (3)=NCAC, Torun (4)=Univ. of Crete

"OPTIMA-Burst at the 1.3m Skinakas Observatory of the University of
Crete, Greece continued observations of the OT associated with SWIFT 
J195509.6+261406 (GRB 070610).

On 2007-06-12 we observed the source during 21:00-23:10 UT, using our 
photon counting mode. In this period we detected flaring activity 
consisting of only four short, dim flares:

t_start      duration   approx peak mag.
21:55:45     16s        18.9
22:23:13     18s        18.7
22:26:33     45s        18.4
22:34:14     17s        19.2


On 2007-06-13 we observed the source between 20:15-20:43 UT and 
20:59-22:10 UT. We did not detect any flaring activity, the source 
stayed below the background level detected by our photon counters at all 
times. The brightness of a fluctuation 1 sigma above background noise 
corresponds roughly to 21.4 mag.

We conclude that the flaring activity of the optical counterpart of 
SWIFT J195509.6+261406 (GRB 070610) is greatly diminished, or may have 
even come to an end."

This message may be cited.

[GCN OPS NOTE(17jun07):  Per author's request, the two epoch dates
were corrected from "2007-06-13" to "2007-06-12" in the 2nd paragraph
and from "2007-06-14" to "2007-06-13" in the 3rd paragraph.]