SHELS: Complete Redshift Surveys of Two Widely Separated Fields
  The SHELS (Smithsonian Hectospec Lensing Survey) is a complete redshift
survey covering two well-separated fields (F1 and F2) of the Deep Lens Survey.
Both fields are more than 94% complete to a Galactic extinction corrected R0 =
20.2. Here we describe the redshift survey of the F1 field centered at R.A. =
00h53m25.3s and Decl = 12d33m55s; like F2, the F1 field covers 4 sq deg. The
redshift survey of the F1 field includes 9426 new galaxy redshifts measured
with Hectospec on the MMT (published here). As a guide to future uses of the
combined survey we compare the mass metallicity relation and the distributions
of D4000 as a function of stellar mass and redshift for the two fields. The
mass-metallicity relations differ by an insignificant 1.6 sigma. For galaxies
in the stellar mass range 1.e10 to 1.e11 MSun, the increase in the star-forming
fraction with redshift is remarkably similar in the two fields. The seemingly
surprising 31-38% difference in the overall galaxy counts in F1 and F2 is
probably consistent with the expected cosmic variance given the subtleties of
the relative systematics in the two surveys. We also review the Deep Lens
Survey cluster detections in the two fields: poorer photometric data for F1
precluded secure detection of the single massive cluster at z = 0.35 that we
find in SHELS. Taken together the two fields include 16,055 redshifts for
galaxies with R0 <= 20.2 and 20,754 redshifts for galaxies with R <= 20.6.
These dense surveys in two well-separated fields provide a basis for future
investigations of galaxy properties and large-scale structure.
