The IMACS Cluster Building Survey. I. Description of the Survey and
  Analysis Methods
  The IMACS Cluster Building Survey uses the wide field spectroscopic
capabilities of the IMACS spectrograph on the 6.5m Baade Telescope to survey
the large-scale environment surrounding rich intermediate-redshift clusters of
galaxies. The goal is to understand the processes which may be transforming
star-forming field galaxies into quiescent cluster members as groups and
individual galaxies fall into the cluster from the surrounding supercluster.
This first paper describes the survey: the data taking and reduction methods.
We provide new calibrations of star formation rates derived from optical and
infrared spectroscopy and photometry. We demonstrate that there is a tight
relation between the observed star formation rate per unit B luminosity, and
the ratio of the extinctions of the stellar continuum and the optical emission
lines. With this, we can obtain accurate extinction-corrected colors of
galaxies. Using these colors as well as other spectral measures, we determine
new criteria for the existence of ongoing and recent starbursts in galaxies.
