TITLE: GCN GRB OBSERVATION REPORT NUMBER: 5190 SUBJECT: GRB 051028 : WIDGET pre-trigger limit DATE: 06/05/31 11:41:11 GMT FROM: Toru Tamagawa at RIKEN K. Masuno, Y. Urata, M. Tashiro, K. Abe, K. Onda, N. Kodaka (Saitama-U), F. Usui (ISAS/JAXA), M. Kuwahara (TUS/RIKEN), T. Tamagawa (RIKEN) report: "We observed the error region of GRB 051028 (Hurley et al. GCN 4172) with the very wide-field camera WIDGET located at Akeno, Japan. WIDGET monitored the region with repeat of unfiltered 5-second exposures between 16.0 min and 11.2 min before the burst. We did not find any optical emission from the afterglow position (Jelinek et al. GCN 4175). The 1-sigma limiting magnitude of each frame derived by the Tycho-2 catalog was around V=10.3 magnitudes." This message may be cited.