Multi-color Shallow Decay and Chromatic Breaks in the GRB 050319 Optical   Afterglow
  Multi-wavelength B, V, R, I observations of the optical afterglow of GRB 050319 were performed by the 1.05-m telescope at Kiso Observatory and the 1.0-m telescope at Lulin Observatory from 1.31 hours to 9.92 hours after the burst. Our R band lightcurves, combined with other published data, can be described by the smooth broken power-law function, with $\alpha_1$ = -0.84 $\pm$0.02 to $\alpha_2$ = -0.48$\pm$0.03, 0.04 days after the GRB. The optical lightcurves are characterized by shallow decays-- as was also observed in the X-rays-- which may have a similar origin, related to energy injection. However, our observations indicate that there is still a puzzle concerning the chromatic breaks in the R band lightcurve (at 0.04 days) and the X-ray lightcurve (at 0.004 days) that remains to be solved. 
K.Y. Huang, Y. Urata, P.H. Kuo, W.H. Ip, K. Ioka, T. Aoki, C.W. Chen,   W.P. Chen, M. Isogai, H.C. Lin, K. Makishima, H. Mit...