TITLE: GCN GRB OBSERVATION REPORT NUMBER: 416 SUBJECT: GRB 990915 optical observations DATE: 99/09/26 09:13:19 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA GRB 990915, optical observations --------------------------------- Alberto Castro-Tirado, LAEFF-INTA (Madrid) and IAA-CSIC (Granada) on behalf of a large collaboration: Victor Costa and Jose L. Ortiz, IAA-CSIC Oliver Cordes, Martin Altmann and Daniel Harbeck, Univ. of Bonn Javier Gorosabel, LAEFF-INTA Mara Salvato and Jochen Greiner, AIP (Potsdam) Kevin Hurley, UCBerkeley/SSL reports: "Following the detection of the strong burst GRB 990915 by BATSE and COMPTEL (Batse trigger # 7766) we have obtained: -150 frames (60-s, no filter, 20' x 13' FOV) at the 0.8-m Schmidt telescope of the German-Spanish Calar Alto Observatory (CAHA) starting 0.5 hr after the burst. The frames covered a significant fraction of the Hunstville/Locburst and COMPTEL error boxes and about a 15 % of the NEAR error box given by Hurley et al. in GCN 412. -25 frames (60-s, R-band, 16' x 16' FOV) at the 1.23-m CAHA telescope starting 30 hr after the burst. The frames covered an additional fraction (65 %) of the NEAR error box. -10 frames (150-s, R-band) at the 1.23-m CAHA telescope starting 50 hr after the burst. The frames covered the rest (20 %) of the NEAR error box. After a careful visual comparison with the Digital Sky Survey, I have not found any source varying more than 0.3 mag when comparing to the DSS-1 charts, i.e. a limit of R > 20.5 can be imposed to the GRB 990915 optical afterglow."