Hubble Space Telescope and Ground-Based Optical and Ultraviolet Observations of GRB010222

We report on Hubble Space Telescope WFPC2 optical and STIS near ultraviolet MAMA observations, and ground-based optical observations of GRB010222, spanning 15 hrs to 71 days. The observations are well-described by a relativistic blast-wave model with a hard electron-energy distribution, p = 1.57 −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 Hubble Space Telescope 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 GRB010222. 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 to the Hydrogen column inferred from X-ray observations, we suggest that this is evidence for dust destruction. Subject headings: gamma rays: bursts Division of Physics, Mathematics and Astronomy, California Institute of Technology, MS 105-24, Pasadena, CA 91125 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 Laboratory for Astronomy and Solar Physics, NASA Goddard Space Flight Center, Code 681, Greenbelt, MD 20771 National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801 School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel California Institute of Technology, Theoretical Astrophysics 103-33, Pasadena, CA 91125 Division of Physics, Mathematics and Astronomy, 105-24, California Institute of Technology, Pasadena, CA, 91125.