The Frontier Fields: Survey Design
  The Frontier Fields are a director's discretionary time campaign with HST and
the Spitzer Space Telescope to see deeper into the universe than ever before.
The Frontier Fields combine the power of HST and Spitzer with the natural
gravitational telescopes of massive high-magnification clusters of galaxies to
produce the deepest observations of clusters and their lensed galaxies ever
obtained. Six clusters - Abell 2744, MACSJ0416.1-2403, MACSJ0717.5+3745,
MACSJ1149.5+2223, Abell S1063, and Abell 370 - were selected based on their
lensing strength, sky darkness, Galactic extinction, parallel field
suitability, accessibility to ground-based facilities, HST, Spitzer and JWST
observability, and pre-existing ancillary data. These clusters have been
targeted by the HST ACS/WFC and WFC3/IR with coordinated parallels of adjacent
blank fields for over 840 HST orbits. The Spitzer Space Telescope has dedicated
> 1000 hours of director's discretionary time to obtain IRAC 3.6 and 4.5 micron
imaging to ~26.5, 26.0 ABmag 5-sigma point-source depths in the six cluster and
six parallel Frontier Fields. The Frontier Field parallel fields are the
second-deepest observations thus far by HST with ~29th ABmag 5-sigma point
source depths in seven optical - near-infrared bandpasses. Galaxies behind the
Frontier Field cluster lenses experience typical magnification factors of a
few, with small regions near the critical curves magnified by factors 10-100.
Therefore, the Frontier Field cluster HST images achieve intrinsic depths of
~30-33 magnitudes over very small volumes. Early studies of the Frontier Fields
have probed galaxies fainter than any seen before during the epoch of
reionization 6 < z < 10, mapped out the cluster dark matter to unprecedented
resolution, and followed lensed transient events.
