GCN Circular 1500
D. Malesani and S. Covino (INAF, Merate Obs., Milan), D. Fugazza and R. Barrena (TNG), E. Pian and N. Masetti (IASF/CNR, Bologna), on behalf of a larger collaboration, report: We observed the optical counterpart of GRB 020813 on Aug 13.99, 15.04 and 16.03 UT, using the VLT and TNG telescopes and a standard Bessel V filter. The source is clearly detected and it shows a fading by 1.04 +/- 0.05 magnitudes between the first and the second epoch, and by 0.62 +/- 0.10 magnitudes between the second and third epoch. The afterglow is hence decaying with time according to a sharply defined power-law with a slope of delta = -1.4 +/- 0.02. The break in the decay suggested in GCN #1476 (Bloom, Fox & Hunt) and #1491 (Li, Chornock & Filippenko) is therefore confirmed. Complete analysis of the photometric data is underway. This message can be cited.