TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4296 SUBJECT: GRB 051109B: GAO 150cm telescope Optical limit DATE: 05/11/22 06:13:34 GMT FROM: Kenzo Kinugasa at Gunma Astro. Obs/Japan K. Kinugasa (Gunma Astronomical Observatory) and K. Torii (Osaka U.) report: The error region of GRB 051109B (Tagliaferri, et al. GCN 4222) was imaged with the LN2 cooled CCD Camera atattched on the 150 cm telescope of the Gunma Astronomical Observatory. Starting at 15:28 UT (6.8 hours after the burst), V, Rc, and Ic frames were acquired. We do not identify an optical counterpart for the X-ray afterglow (Campana, et al. GCN 4226). Following 3-sigma upper limits are derived for the stacked frames relative to USNO-B1.0 magnitudes. --------------------------------- MidUT Filter Mag Exposure --------------------------------- 15:54 Rc >20.2 180s x 5 16:10 Ic >18.4 60s x 10 ---------------------------------