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 Fv ∝ t-1±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 Fv ∝ v-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.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science