Unusually rapid variability of the GRB000301C optical afterglow
  We present BVRI light curves of the afterglow of GRB000301C, one of the brightest ever detected at a day time scale interval after GRB trigger. The monitoring started 1.5 days after the GRB and ended one month later. Inspection of the extremely well sampled R band light curve and comparison with BVI data has revealed a complex behavior, with a long term flux decrease and various short time scale features superimposed. These are uncommon among other observed afterglows, and might trace either intrinsic variability within the relativistic shock (re-acceleration and re-energization) or inhomogeneities in the medium in which the shock propagates. 
N. Masetti, et al