An Efficient Approach to Obtaining Large Numbers of Distant Supernova
  Host Galaxy Redshifts
  We use the wide-field capabilities of the 2dF fibre positioner and the
AAOmega spectrograph on the Anglo-Australian Telescope (AAT) to obtain
redshifts of galaxies that hosted supernovae during the first three years of
the Supernova Legacy Survey (SNLS). With exposure times ranging from 10 to 60
ksec per galaxy, we were able to obtain redshifts for 400 host galaxies in two
SNLS fields, thereby substantially increasing the total number of SNLS
supernovae with host galaxy redshifts. The median redshift of the galaxies in
our sample that hosted photometrically classified Type Ia supernovae (SNe Ia)
is 0.77, which is 25% higher than the median redshift of spectroscopically
confirmed SNe Ia in the three-year sample of the SNLS. Our results demonstrate
that one can use wide-field fibre-fed multi-object spectrographs on 4m
telescopes to efficiently obtain redshifts for large numbers of supernova host
galaxies over the large areas of sky that will be covered by future
high-redshift supernova surveys, such as the Dark Energy Survey.
