TITLE: GCN GRB OBSERVATION REPORT NUMBER: 786 SUBJECT: GRB000830, TNG B-band observations DATE: 00/09/04 14:32:03 GMT FROM: Nicola Masetti at ITeSRE,CNR,Bologna E. Palazzi, N. Masetti (ITESRE, CNR, Bologna), A. Magazzu, M. Pedani, S. Benetti (TNG) and E. Pian (OATs, Trieste), on behalf of a larger collaboration, report: "We acquired optical B-band images of the central part of the GRB000830 error box (Hurley et al., GCN #779) on 2000 Aug. 31.99, Sep. 2.03 and Sep. 3.16 UT (i.e. 24, 49 and 76 hours after the GRB) with TNG+Dolores. The total exposure time was 15 minutes for each epoch. Seeing was 1.2, 1.1 and 1.5 arcsec on the three epochs, respectively. The pointings covered about 75% of the GRB error box. Photometric calibration was performed using USNO-A2.0 catalog stars. No new object brighter than the DSS-II limit is detected inside the GRB error box in any of the three images (note however that the DSS-II plates are in the R-band filter). Also, the comparison between pairs of epochs does not reveal any object with significant brightness variation down to a 3-sigma limiting magnitude B ~ 24.0.". This message can be cited.