TITLE: GCN GRB OBSERVATION REPORT NUMBER: 439 SUBJECT: GRB 991105, optical observations DATE: 99/11/08 18:34:21 GMT FROM: Alberto Castro-Tirado at Inst.de Astrofisica de Andaluciaajct@iaa.es GRB 991105, optical observations Alberto Castro-Tirado, LAEFF-INTA (Madrid) and IAA-CSIC (Granada) Javier Gorosabel and Celia Sanchez-Fernandez, LAEFF-INTA (Madrid) Pam Kilmartin and John Hearnshaw, University of Canterbury Ian Bond, Nick Rattembury and Phil Yock, University of Auckland K. Ohnishi, Nagano National College of Technology and Marco Feroci, IAS (Frascati), on behalf of the BSAX team report: "We have obtained six 10-minute exposures at the revised BeppoSAX WFC position for GRB 991105 (Piro et al. GCN 433) with the 0.61-m Mount John University Observatory (MJUO) telescope. The first set of images were taken on Nov 6.41 UT (17.1 hr after the GRB) through a broad band filter (R + I bandpass). The second one was obtained on Nov 7.37 UT with identical setup. After a visual comparison with the Digital Sky Survey and among the two co-added images, no sources varying by more than 0.3 mag were seen to the DSS limit (R about 21) within the BeppoSAX error box." This message can be cited.