TITLE: GCN GRB OBSERVATION REPORT NUMBER: 118 SUBJECT: GRB980613, optical observations DATE: 98/06/22 15:26:21 GMT FROM: Vladimir Sokolov at SAO RAS V. Sokolov, S. Zharikov on behalf of the SAO-RAS GRB follow-up team and L. Piro, E. Costa, L. Nicastro and E. Palazzi on behalf of the SAX GRB team report: On Jun. 20.858 we obtained Rc band images with the 6-m BTA telescope of SAO-RAS. We detected the source reported by Hjorth et al. (GCN #109). Conditions were not photometric with seeing of 3.0 arcsec. The total observing time was 3600 s with 600 s per exposure. For photometric calibration we used star 1 from Hjorth et al. (GCN #109) and star 4_r from Odewahn et al. (GCN #105) (assuming r-R=0.35). Preliminary photometry (Cousins R) of the source yields: June 20.858 UT: Rc = 23.17+/-0.08 This result is not consistent with the upper limit of June 17.9088 UT: R > 24.0 (formal 10-sigma limit) from Hjorth et al. (GCN #109). Finding charts and updates of these preliminary results will be posted at http://www.sao.ru/~zhar/home/GRB/980613.html This message can be cited.