The discovery of an optical counterpart to GRB 010222 (detected by BeppoSAX) was announced 4.4 hr after the burst by Henden. The Sloan Digital Sky Survey's 0.5 m photometric telescope (PT) and 2.5 m survey telescope were used to observe the afterglow of GRB 010222 starting 4.8 hr after the gamma-ray burst. The 0.5 m PT observed the afterglow in five 300 s g*-band exposures over the course of half an hour, measuring a temporal decay rate in this short period of Fν ∝ t-1.0±0.5. The 2.5 m camera imaged the counterpart nearly simultaneously in five filters (u*,?g*,?r*,?i*,?z*), with r* = 18.74 ± 0.02 at 12:10 UT. These multicolor observations, corrected for reddening and the afterglow's temporal decay, are well-fitted by the power law Fν ∝ ν-0.90±0.03 with the exception of the u*-band UV flux which is 20% below this slope. We examine possible interpretations of this spectral shape, including source extinction in a star-forming region.
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机译：Henden爆炸发生4.4小时后，宣布发现了GRB 010222光学配对物（由BeppoSAX检测）。 Sloan Digital Sky Survey的0.5 m光度望远镜（PT）和2.5 m测量望远镜用于观察伽玛射线爆发后4.8小时开始的GRB 010222余辉。 0.5 m PT在半小时内观察了五次300 s g *波段曝光后的余辉，测量了这短暂的Fν∝ t-1.0±0.5时间内的时间衰减率。该2.5 m相机几乎同时在五个滤镜（u * 、? g * 、? r * 、? i * 、? z *）中对对方进行成像，在UT 12:10时r * = 18.74±0.02。这些经过多色观测的，经过修正的变红和余辉的时间衰减，通过幂定律Fννν-0.90±0.03可以很好地拟合，但u *波段的紫外线通量比该斜率低20％。我们研究了这种光谱形状的可能解释，包括在恒星形成区域内的源消光。
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