TITLE: GCN GRB OBSERVATION REPORT NUMBER: 2254 SUBJECT: GRB 030329: Optical Observations DATE: 03/05/28 18:42:55 GMT FROM: Haw Cheng at UNC H. Cheng, M. Bayliss, D. Reichart, J. Moran, M. Nysewander, M. Schwartz, and P. Holvorcem report on behalf of the UNC GRB team of the FUN GRB collaboration: We observed the afterglow (Peterson & Price, GCN 1985) of GRB 030329 (Vanderspek et al., GCN 1997) with the 32-inch Tenagra II telescope in IcRcVIc on April 2nd and 3rd, in IcIc on April 4th and 5th, and in Ic on April 6th, 7th, 8th, 9th, and 10th. Between April 2nd and 10th, we find that the afterglow faded from Ic = 16.9 mag to Ic = 18.9 mag. Our 1-sigma error bars are typically less than 0.02 mag. Fitting a four-parameter model to the data, where the parameters are the temporal index alpha, the spectral index beta, a normalization parameter, and a parameter that measures the level of of systematic (i.e., non-statistical) fluctuations in the light curve, we find that alpha = -1.70(+0.13)(-0.14), beta = -1.38(+0.20)(-0.20), and that the fading afterglow is fluctuating at the 17.5(+3.8)(-3.5)% level at these times. We note that the measured spectral index is too steep given the measured temporal index and the post-jet break time relations of Sari, Piran, & Halpern (1999, ApJ, 519, L17). Possible explanations include: 1. The light curve had not yet reached its asymptotic temporal index, which if the afterglow is unextinguished would be alpha = -2.76 +- 0.20 if the cooling break is redward of the observed bands or alpha = -3.76 +- 0.20 if the cooling break is blueward of the observed bands; or 2. The light curve is extinguished. Although this does not appear to be the case at earlier times, this could be the case at later times if dust was destroyed within the initial opening angle of the jet, but then the jet expanded laterally behind undisturbed dust.