GRB 080517: A local, low luminosity GRB in a dusty galaxy at z=0.09
  We present an analysis of the photometry and spectroscopy of the host galaxy
of Swift-detected GRB 080517. From our optical spectroscopy, we identify a
redshift of z = 0.089 +/- 0.003, based on strong emission lines, making this a
rare example of a very local, low luminosity, long gamma ray burst. The galaxy
is detected in the radio with a flux density of S(4.8GHz) =0.22 +/- 0.04mJy -
one of relatively few known GRB hosts with a securely measured radio flux. Both
optical emission lines and a strong detection at 22 um suggest that the host
galaxy is forming stars rapidly, with an inferred star formation rate ~16
Msun/yr and a high dust obscuration (E(B-V )>1, based on sight-lines to the
nebular emission regions). The presence of a companion galaxy within a
projected distance of 25 kpc, and almost identical in redshift, suggests that
star formation may have been triggered by galaxy-galaxy interaction. However,
fitting of the remarkably flat spectral energy distribution from the
ultraviolet through to the infrared suggests that an older, 500Myr
post-starburst stellar population is present along with the ongoing star
formation. We suggest that that the host galaxy of GRB 080517 is a valuable
addition to the still very small sample of well-studied local gamma-ray burst
hosts.
