TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3376 SUBJECT: GRB 050505: early time observations DATE: 05/05/07 22:28:55 GMT FROM: Alberto Castro-Tirado at LAEFF-INTA A. de Ugarte Postigo, M. Jelinek, J. Gorosabel (IAA-CSIC Granada), P. Kubanek, R. Hudec (ASU-CAS Ondrejov), T. J. Mateo Sanguino (Univ. de Huelva), S. Castillo, S.Guziy and A. J. Castro-Tirado (IAA-CSIC), report: "Following the detection by SWIFT/BAT of GRB 050505 (Herkett et al., GCN 3360), the pair of 0.2m BOOTES-1B telescopes at INTA-CSIC's Observatorio de Arenosillo responded automatically at 23:32:30 UT (i.e. 70 s after the alert which was received 9.5 min after the onset of the event). A co-addition of the first V- and I-band images taken do not reveal the optical afterglow at the position given by Bradley Cenko et al., (GCN 3366). On the other hand, the 0.6m telescope (+BOOTES-IR optical camera) at IAA's Observatorio de Sierra Nevada responded automatically at 23:31:57 UT (i.e. 37 s after the alert received 9.5 min after the onset of the event). Due to technical problems (the telescope is still in commissioning phase), the first image was acquired at 00:09 UT (47 min after the GRB). A preliminary analysis of our R-band observations (total exposure time = 1 hour) imposes a limit of R > 19 to the afterglow optical emission (Bradley Cenko et al., GCN 3366). Further analysis is in progress." This message may be cited.