This document describes the exposure time calculator for the Wide-Field
Infrared Survey Telescope (WFIRST) high-latitude survey. The calculator works
in both imaging and spectroscopic modes. In addition to the standard ETC
functions (e.g. background and S/N determination), the calculator integrates
over the galaxy population and forecasts the density and redshift distribution
of galaxy shapes usable for weak lensing (in imaging mode) and the detected
emission lines (in spectroscopic mode). The source code is made available for
public use.Comment: 44 pages. The current C source code and version history can be found
at http://www.tapir.caltech.edu/~chirata/web/software/space-etc/ ; IPAC
maintains a web interface at
http://wfirst-web.ipac.caltech.edu/wfDepc/wfDepc.js
