TITLE: GCN GRB OBSERVATION REPORT NUMBER: 579 SUBJECT: GRB 000301C R-band observation DATE: 00/03/04 02:51:37 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia Alberto J. Castro-Tirado, IAA-CSIC (Granada) Holger Bock, Landesternwarte (Heidelberg) Jochen Greiner, AIP (Potsdam) Sylvio Klose, TLS (Tautenburg) Jose Maria Castro Ceron, ROA (San Fernando) Felipe Hoyo, CAHA (Almeria) Javier Gorosabel, DSRI (Copenhagen) on behalf of a larger European GRB collaboration report: "We have just obtained a 15-minute R-band exposure centred at the GRB 000301C error box (Smith et al. GCN#568) starting at 01:15 UT on 4 March 2000 with the 1.23 m telescope at the German-Spanish Calar Alto Observatory (CAHA). Using the stars A-D of Garnavich et al. (GCN #573) we derive R = 20.46 +/- 0.09 for the optical counterpart reported by Fynbo et al. (GCN #570). When combining this value with the measurements by Fynbo et al. (GCN #576) and Halpern et al. (GCN #578) the power-law decline exponent becomes alpha = -1.27 +/- 0.20." This message is quotable. [GCN OPS NOTE (03Mar00): The Felipe Hoyo author was added to the archive copy.]