[vsnet-grb-info 11328] GRB 111225A, optical observations

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  12740
SUBJECT: GRB 111225A, optical observations
DATE:    11/12/28 18:26:56 GMT
FROM:    Eda Sonbas at NASA/GSFC  <edasonbas at gmail.com>

TITLE: T100 observations of GRB 111225A

Sonbas, E.(Adiyaman Univ.), Guver, T. (Sabanci Univ.), Gogus, E. (Sabanci
Univ.),
Uysal, O. (Akdeniz Univ.), Sahin T. (Akdeniz Univ.), Eker, Z. (TUG), T.
Ozisik (TUG) on behalf of a larger collaboration.


We observed the field of GRB 111225A (Siegel et al., GCN #12720) with the
1.0 meter T100 telescope (TUBITAK National
Observatory, Antalya - Turkey), starting on December 25, 21:14 UT (~ 17
hours after the trigger). We obtained
3 x 60 s + 2 x 300 s exposures with R and B filters under moderate weather
conditions (seeing 1.8").

We do not detect an optical afterglow at the enhanced XRT error circle
reported by Evans et al., GCN #12724
in the combined R and B band images. We determine the following 3-sigma
upper limits (calibrated to R2 and B2 mag. of USNO-B1)
in the two bands:

   t - t0        Exposure (s)          Filter              mag.
~17.4 h           780                    R                 > 22.5
~17.5 h           780                    B                 > 21.9

We are grateful to the TUBITAK National Observatory staff for promptly
scheduling the observations and their
technical support.