TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2571 SUBJECT: GRB 040403, deep optical observations DATE: 04/04/22 07:37:37 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia GRB 040403, deep optical observations ---------------------------------------------- A. de Ugarte, A. Sota, J. Gorosabel and A. J. Castro-Tirado (Instituto de Astrofísica de Andalucía, IAA-CSIC, Granada), and J. M. Castro Cerón (STScI, Baltimore) communicate: "We observed the field of the X-ray rich GRB 040403 detected by INTEGRAL (GCN Circ. 2560, Gotz et al.) starting on 3 Apr 2004 (20:00 UT) with the 1.5 m telescope at the Observatorio de Sierra Nevada in Granada. Imagery was obtained in the R- band (6 x 600 s). Comparison images were adquired on 4 and 20 Apr 2004 (9 x 600 s). No optical variable source is detected within the 3' radius error box provided by IBIS/IGRIS down to a limiting magnitude of 22.2 (3 sigma) 15 hr after the event. This might be indicative of a dark GRB." This message may be cited.