[vsnet-grb-info 10830] GRB 110726A: two epochs of SAO RAS optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12251
SUBJECT: GRB 110726A: two epochs of SAO RAS optical observations
DATE:    11/08/06 07:04:37 GMT
FROM:    Vladimir Sokolov at SAO RAS  <sokolov at sao.ru>

A.S.Moskvitin, V.V.Sokolov
report on behalf of the SAO RAS GRB follow-up team:

We observed the field of GRB 110726A (Wolf et al., GCN 12196) with two
optical telescopes of SAO RAS: the 1-m Zeiss-1000 on July, 26/27 in B
and Rc bands and the 6-m BTA + Scorpio on July, 29/30 in Rc band.
We clearly detected an optical transient at the place reported by
Schaefer, Zheng & Flewelling (GCN Circ. 12197, ROTSE-III) and
Siegel & Wolf (GCN Circ. 12199, Swift/UVOT). Results of SAO RAS
observations of OT are presented in the following table.
_______________________________________________________________________
date of July, UT   filter   exp.            magnitude        telescope
_______________________________________________________________________
26.833 -- 27.017   Rc       17 x 300 sec.   22.17 +/- 0.12   Zeiss-1000
26.856 -- 27.022   B        16 x 300 sec.   23.47 +/- 0.17   Zeiss-1000
29.819 -- 29.861   Rc       15 x 180 sec.   23.34 +/- 0.09   BTA
_______________________________________________________________________

We use USNO-B.1 1460-0295684 (R. A. = 19:06:51.53, Dec. =  +56:04:41.2,
Epoch = 2000.0) with the magnitudes B2 = 20.39, R2 = 18.06
(Gorosabel et al. GCN Circ. 12206) as the reference star.

At the BTA image (ftp://ftp.sao.ru/pub/grb/GRB110726A/GRB110726A_BTA.jpeg)
we detected one more faint object with R = 25.21 +/- 0.30, located 3.5"
North-East from the Swift/UVOT position. According to the Gemini-N redshift
range 1.036 < z < 2.7 reported by Cucchiara Bloom & Cenko (GCN Circ. 12202)
this angle size corresponds to (110 -- 370) +/- 20 kpc.

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