TITLE: GCN GRB OBSERVATION REPORT NUMBER: 766 SUBJECT: GRB000301C, UBVI optical observations DATE: 00/08/03 04:01:59 GMT FROM: Krzysztof Z. Stanek at CfA K. Z. Stanek (CfA), P. Garnavich (Notre Dame), P. Barmby, S. Jha (CfA) report: Given the microlensing interpretation of GRB000301C (Garnavich, Loeb & Stanek 2000b: astro-ph/0008049) and the importance of any additional data for this burst, we reduced several additional frames of the optical counterpart of GRB000301C obtained with the FLWO 1.2m telescope and UBVI filters on 2000 Mar. 4 (UT). Our measurements are based on the comparison star A of Garnavich et al. (2000a: GCN 573), calibrated by Henden (2000: GCN 583) (magnitudes given by Jensen et al. 2000: astro-ph/0005609). We obtain the following values: Mar. 4.5097 UT U=20.89 \pm 0.13 Mar. 4.499 UT B=21.49 \pm 0.05 Mar. 4.478 UT V=20.98 \pm 0.05 Mar. 4.485 UT I=20.28 \pm 0.07 As discussed by Garnavich et al. (2000b), to take full advantage of this unique burst a uniform reduction of all CCD data available would be most desired. To encourage such an endeavor, we make all our CCD data (seven 1kx1k frames; see also GCN 573 and 581) publicly available through the anonymous ftp at ftp://cfa-ftp.harvard.edu/pub/kstanek/GRB000301C/ Please contact K. Z. Stanek (kstanek@cfa.harvard.edu) if you have any questions concerning the data. This message can be cited.