A Revised Host Galaxy Association for GRB 020819B: A High-Redshift Dusty
  Starburst, Not a Low-Redshift Gas-Poor Spiral
  The purported spiral host galaxy of GRB 020819B at z=0.41 has been seminal in
establishing our view of the diversity of long-duration gamma-ray burst
environments: optical spectroscopy of this host provided evidence that GRBs can
form even at high metallicities, while millimetric observations suggested that
GRBs may preferentially form in regions with minimal molecular gas. We report
new observations from VLT (MUSE and X-shooter) which demonstrate that the
purported host is an unrelated foreground galaxy. The probable radio afterglow
is coincident with a compact, highly star-forming, dusty galaxy at z=1.9621.
The revised redshift naturally explains the apparent nondetection of CO(3-2)
line emission at the afterglow site from ALMA. There is no evidence that
molecular gas properties in GRB host galaxies are unusual, and limited evidence
that GRBs can form readily at super-Solar metallicity.
