TITLE: GCN GRB OBSERVATION REPORT NUMBER: 4285 SUBJECT: GRB 051117B: Lulin R and I band observation DATE: 05/11/17 18:18:52 GMT FROM: Yuji Urata at RIKEN GRB 051117B: Lulin R and I band observation Y.T. Chen, K.Y. Huang, W.H. Ip (NCU), Y. Urata(RIKEN), Y. Qiu (BAO), Y.Q. Lou (THCA) on behalf of EAFON report: " We started R and I band imaging observation for GRB 051117B (Band et al., GCN 4281) with Lulin 1-m telescope at 14:11 UT (48 minutes after the burst). The stacked I-band image made from 9 x 300 s exposure shows a very faint sources at RA=05:40:43.3 Dec=-19:16:26(edge of Swift/XRT error region; Beardmore et al. GCN4282). The brightness calibrated with USNO-B1.0 catalog is about I=20.6. We could not find this source in stacked R-band image made from 3 x 300 s exposure brighter than R < 20.8 (SN=3). Further observation and analysis are in progress." This message may be cited.