Hubble Space Telescope and Ground-based Optical and Ultraviolet Observations of GRB 010222
Price, P. A.; Harrison, F. A.; Galama, T. J.; Berger, E.; Bloom, J. S.; Djorgovski, S. G.; Frail, D. A.; Gal-Yam, A.; Kulkarni, S. R.; Sari, R.; Brown, T. M.; Kimble, R. A.; Reichart, D.; Yost, S. A.; Fox, D.
United States, Israel
Abstract
We report on Hubble Space Telescope (HST) Wide Field Planetary Camera 2 optical and Space Telescope Imaging Spectrograph (STIS) near-ultraviolet MAMA observations and ground-based optical observations of GRB 010222, spanning 15 hr to 71 days. The observations are well described by a relativistic blast wave model with a hard electron energy distribution, p=1.57+0.04-0.03, and a jet transition at t*=0.93+0.15-0.06 days. These values are slightly larger than previously found as a result of a correction for the contribution from the host galaxy to the late-time ground-based observations and the larger temporal baseline provided by the HST observations. The host galaxy is found to contain a very compact core (size <0.25"), which coincides with the position of the optical transient. The STIS near-ultraviolet MAMA observations allow for an investigation of the extinction properties along the line of sight to GRB 010222. We find that the far-ultraviolet curvature component c4 is rather large. In combination with the low optical extinction, AV=0.110+0.010-0.021 mag, when compared with the hydrogen column inferred from X-ray observations, we suggest that this is evidence for dust destruction.