TITLE: GCN GRB OBSERVATION REPORT NUMBER: 720 SUBJECT: GRB000607, optical observations DATE: 00/06/20 15:14:00 GMT FROM: Nicola Masetti at ITeSRE,CNR,Bologna N. Masetti, E. Palazzi, E. Pian (ITESRE, CNR, Bologna), A.J. Castro-Tirado (LAEFF, IAA), R. Hudec, J. Soldan (ASU, Ondrejov), M. Bernas and P. Pata (CVUT-FEL, Prague), J.M. Castro Ceron (ROA, San Fernando), C. Kouveliotou (USRA), J. Hjorth (Univ. of Copenhagen), P.M. Vreeswijk, E.P.J. van den Heuvel (Univ. of Amsterdam), J. Greiner (AIP), M. Zoccali (Univ. of Padua) and O. Hainaut (ESO), on behalf of larger collaborations, report: "We have obtained several unfiltered images of the IPN error box for the short, hard burst GRB000607 (Hurley et al., GCN 693), with the narrow-field CCD attached to the 0.3-m telescope of BOOTES-1 at El Arenosillo (Spain) on Jun 9.24 UT (51 hr after the event, 360 sec exposure time). The limiting magnitude of the summed image, covering the whole error box, is ~16 due to the very poor observing conditions (the GRB field was imaged close to dawn). None of the single images, as well as their sum, reveals any new, or strongly variable, source when compared with the Digital Sky Survey (DSS-II). We also acquired an optical R-band image of northern part of the error box of this GRB just before dawn on 2000 June 9.44 UT (i.e. ~56 hr after the GRB trigger) with the 1.54-meter Danish telescope (plus DFOSC) at ESO - La Silla (Chile). Seeing was ~2 arcsec, and exposure time was 450 sec. This image also could not be very deep as it was obtained during twilight due to the unfavourable position of this GRB with respect to the Sun; indeed, the southern part of the error box could not be imaged because of a too high sky level. Photometric calibration was performed using USNO-A1.0 field stars. The comparison with the DSS-II survey does not reveal any new or substantially variable object brighter than R ~ 19.5.". This message can be cited.