Keck Deep Fields . I . Observations , Reductions , and the Selection of Faint Star - Forming Galaxies at Redshifts

We introduce a very deep, Rlim∼27, multicolor imaging survey of very faint star-forming galaxies at z∼4, z∼3, z∼2.2, and z∼1.7. This survey, carried out on the Keck I telescope, uses the very same UnGRI filter system that is employed by the Steidel team to select galaxies at these redshifts, and thus allows us to construct identically-selected, but much fainter, samples. However, our survey reaches ∼1.5 mag deeper than the work of Steidel and his group, letting us probe substantially below the characteristic luminosity Land thus study the properties and redshift evolution of the faint component of the high-z galaxy population. The survey covers 169 arcmin in three spatially independent patches on the sky and — to R≤27 — contains 427 GRI-selected z∼4 Lyman Break Galaxies, 1481 UnGR-selected z∼3 Lyman Break Galaxies, 2417 UnGR-selected z∼2.2 star-forming galaxies, and 2043 UnGR-selected z∼1.7 star-forming galaxies. In this paper, the first in a series, we introduce the survey, describe our observing and data reduction strategies, and outline the selection of our z∼4, z∼3, z∼2.2, and z∼1.7 samples. Subject headings: cosmology: observations — galaxies: evolution — galaxies: high-redshift — galaxies: starburst — galaxies: statistics