TITLE: GCN GRB OBSERVATION REPORT NUMBER: 735 SUBJECT: GRB 000623, optical observations DATE: 00/06/30 16:15:09 GMT FROM: Javier Gorosabel at LAEFF-INTA, Madrid J. Gorosabel (DSRI, Copenhagen), S. Pascual, J. Gallego, J. Zamorano (UCM, Madrid), A.J. Castro-Tirado (LAEFF-INTA, Madrid, and IAA-CSIC, Granada), J.M. Castro Ceron (ROA, San Fernando), S. Klose (Thueringer Landessternwarte, Tautenburg), J. Greiner (AIP, Potsdam), report on behalf of a larger European collaboration: "R-band images covering 90% of the GRB 000623 error box (GCN #730) were acquired with the 2.2-m CAHA telescope, as follows: Date(UT) T-T0(hr) Exp.(s) Seeing(") Lim. Mag. ------------------------------------------------------------ 24.900 -- 24.908 29.1 120 1.2" 20 27.860 -- 27.876 100.2 240 2.0" 20 ------------------------------------------------------------ Comparison between these two epoch observations did not reveal any object brighter than R ~ 19.7 showing a variation larger than 0.3 mag." This message may be cited