GCN Circular 4259
Kuntal Misra (ARIES, Nainital), Atish P. Kamble (Raman Research Institute, Bangalore), D. K. Sahu, S. Srividya, P. Bama, G.C. Anupama and Mr. S. Vanniarajan (Indian Institute of Astrophysics, Bangalore) on behalf of a larger Indian GRB collaboration We observed the field of GRB 051109A (swift trigger=163136) using the 1-m Sampurnanand Telescope (ST) at ARIES, Naini Tal in Cousins R and I filters and the 2-m Himalayan Chandra Telescope (HCT), IAO, Hanle in Bessell B and V filters, starting nearly 12 hours after the burst. The Optical Transient (OT) mentioned by Rykoff et al. (GCN 4211) is clearly seen in images of 10 minutes exposure time. The preliminary magnitude of the OT in different bands in comparison to 5 nearby USNO-B1.0 stars is: UT Magnitude error Band Telescope used Nov 09.5681 19.449 0.08 I ST Nov 09.5796 20.715 0.09 R ST Nov 09.5463 22.044 0.09 B HCT The OT decayed by ~ 0.6 mag from Nov 09.5681 to Nov 09.7201 UT in R band and by 0.28 mag in B in ~2.4 hrs. Further analysis is in progress. This message may be cited.