GRB 010921: Discovery of the First High Energy Transient Explorer Afterglow
Price, P. A.; Harrison, F. A.; Reichart, D. E.; Berger, E.; Bloom, J. S.; Djorgovski, S. G.; Frail, D. A.; Hurley, K.; Kulkarni, S. R.; Kawai, N.; Ricker, G. R.; Henden, A. A.; Yost, S. A.; Graziani, C.; Atteia, J. -L.; Fenimore, E.; Mahabal, A.; Fox, D. W.; van der Spek, R.
United States, Australia, France, Japan
Abstract
We report the discovery of the optical and radio afterglow of GRB 010921, the first gamma-ray burst afterglow to be found from a localization by the High Energy Transient Explorer satellite. We present optical spectroscopy of the host galaxy, which we find to be a dusty and apparently normal star-forming galaxy at z=0.451. The unusually steep optical spectral slope of the afterglow can be explained by heavy extinction, AV>0.5 mag, along the line of sight to the GRB. Dust with similar AV for the host galaxy as a whole appears to be required by the measurement of a Balmer decrement in the spectrum of the host galaxy.