TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3245 SUBJECT: GRB 050412: Optical limit DATE: 05/04/12 13:17:54 GMT FROM: Ken ichi Torii at RIKEN K. Torii (Osaka U.) reports "The error region of GRB 050412 (Cummings, et al. GCN 3237) was observed with the 0.3-m telescope in the New Mexico Skies observatory. Imaging through clear filter started at 05:48:13 UT (250-s after trigger) and 10 frames of 120-s exposure were obtained. We do not find an optical counterpart to the X-ray source (Tamburelli, et al. GCN 3241) and derive its 3-sigma upper limit relative to USNO-A2.0 (R) mag as follows. MeanEpoch Magnitude Exposure 05:49:13 >18.9 120s 06:00:31 >20.5 10x120s "