GCN Circular 5770
S. B. Cenko, E. O. Ofek, and M. Kasliwal (Caltech) report on behalf of a larger collaboration: We have imaged the field of GRB061028 (Sakamoto et al, GCN 5762) with the Large Format Camera mounted at the prime focus of the 200" Palomar Hale telescope. Images consisted of 4 x 180 s in i' and 3 x 180 s in r' taken at a mean epoch of approximately 28 October 12:30 UT (~ 11 hr after the burst). The afterglow candidate identified by Bloom et al. (S1, GCN 5768) is clearly detected in our i'-band images and marginally detected in an r' coaddition. We measure R ~ 22.4, I ~ 21.0 for this source, with large uncertainties due to photometric calibration (relative to USNO-B R2 and I2 reference). We also find another red source (S2) located several arcseconds to the west of the XRT error circle (Cusumano et al., GCN 5767). The coordinates (J2000.0) of this object are: RA: 06:28:54.8 Dec: +46:17:56.8 We measure R ~ 22.6, I ~ 21.0 for this object, with similarly large photometric uncertainties. We find no sources inside the revised XRT error circle. The 5-sigma limiting magnitudes of our observations are R >~ 22.0, I >~ 22.0. An image of the field will be posted shortly at: http://www.srl.caltech.edu/~cenko/public/grb/grb061028.jpg Further observations are planned to search for variability in these two objects.