[vsnet-grb-info 7000] GRB 081128A: optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8584
SUBJECT: GRB 081128A: optical observations
DATE:    08/11/30 18:00:48 GMT
FROM:    Igor Volkov at Asro.Inst.Slovak Acad.Sciences  <volkov at ta3.sk>

On 2008 November 28 (19:55:36 UT) I began observing the field of GRB 081128A
(Margutti et al. GCN Circ. 8571) with the 0.5m reflector and ST-10XME CCD
camera of Stara Lesna (Slovak Republic) observatory. Observations
consisted of one sequence of 7x300s exposures acquired in standard Rc
system.
In my coadded frame it was not possible to detect a single source inside
the refined XRT error box (Evans et al. GCN Circ. 8573) at the position
RA(J2000)=01:23:13.05, Dec(J2000)=+38:07:38.7 with S/N rate more than 5,
which corresponds to Rc = 20.7. But on the level S/N = 3 one could measure
the object with Rc = 21.6+/- 1.1. So I declare Rc = 20.7 as an upper limit
to the source which could be found within error box. The time of the
middle of the sequence was 20:10:52 UT.
The calibration was performed using the Rc magnitudes of SAO53150 (Scopal
A&A 401, L17–L20, 2003) measured just after GRB 081128A observations. The
nearby to error box star GSC 2813 1599 = 12.66Rc +/-0.04 from this
calibration.
This study was supported by the SAI scholarship.

Igor Volkov, Astronomical Institute of the Slovak Academy of Sciences, 059
60 Tatranská Lomnica, Slovak Republic; e-mail: volkov at ta3.sk

[GCN OPS NOTE(30nov08): This circular was delayed ~17 hrs until the author
was added to the vetted list.]