TITLE: GCN GRB OBSERVATION REPORT NUMBER: 467 SUBJECT: GRB 991208 optical observations DATE: 99/12/17 06:11:35 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia GRB 9901208 ----------- Vijay Mohan, Anil K. Pandey, Ram Sagar and S.B. Pandey (from UPSO, Nainital) and Alberto J. Castro-Tirado (INTA, Madrid and IAA, Granada) -on behalf of a larger European collaboration- report: "We have imaged the field of GRB 991208 with the 2k x 2k CCD camera mounted on the UPSO 104-cm telescope on 1999 Dec 12.0 (UT); Dec 13.0 (UT) and Dec 14.0 (UT) in I photometric passband during photometric sky conditions. The optical transient of the GRB 991208 (Castro-Tirado et al. GCN 452) is fading rapidly about 0.5 mag between Dec 12 and 13. This indicates a power decay index of -2.0. The object has become so faint for our telescope that it is barely visible on the 1 hour CCD image. Thus flux decay in I is almost similar to that in R filter (Jensen et al. GCN 454; Garnavich et al. GCN 456). Calibration of the field is in progress. This message is citable."