The Optical Afterglow of GRB 971214: R and J Photometry

We present an R- and J-band photometry of an optical transient that is likely to be associated with the gamma-ray burst event GRB 971214. Our first measurement took place 13 hr after the gamma-ray event. The brightness decayed with a power-law exponent α=-1.20±0.02, which is similar to those of GRB 970228 andGRB 970508, which had exponents of α=-1.10±0.04 and α=-1.141±0.014, respectively. The transient decayed monotonically during the first 4 days following the gamma-ray event in contrast with the optical transient associated with GRB 970508, which increased in brightness, peaking 2 days after the burst, before settling to a power-law decay.