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Hubble Space Telescope
Frontier Fields

Hubble Deep Field Initiative

HST Observation Schedule

The HST observation schedule is below (click on graphic to browse calendar):

The Implementation Plan

The first four cluster/blank field pairs will be observed with Director's Discretionary time in Cycles 21 and 22. The observations of the final two cluster/blank field pairs in Cycle 23 will be contingent on the initial results from Cycle 21/22. HST will obtain WFC3/IR and ACS images simultaneously for each cluster/parallel blank field at a fixed position angle, and then swap camera positions roughly 6 months later.

The program devotes 140 orbits to each cluster/blank field pair, achieving AB ≈ 28.7-29 mag optical (ACS) and NIR (WFC3) imaging with 560 orbits in Cycles 21/22. Limiting AB mags are for 5-sigma detections of a point source within a 0.4" diameter aperture.

ACS: (70 orbits per position) WFC3/IR: (70 orbits per position)
Filter Orbits AB_mag Filter Orbits AB_mag
F435W 18 28.8 F105W 24 28.9
F606W 10 28.8 F125W 12 28.6
F814W 42 29.1 F140W 10 28.6
      F160W 24 28.7

Frequently Asked Questions

Six Frontier Fields

Cluster Name z Cluster Parallel Field HST
RA Dec RA Dec
Year 1:
Abell 2744 0.308 00:14:21.2 -30:23:50.1 00:13:53.6 -30:22:54.3 Abell 2744 regions
MACSJ0416.1-2403 0.396 04:16:08.9 -24:04:28.7 04:16:33.1 -24:06:48.7 MACSJ0416-2403 regions
Year 2:
MACSJ0717.5+3745 0.545 07:17:34.0 +37:44:49.0 07:17:17.0 +37:49:47.3 MACSJ0717+3745 regions
MACSJ1149.5+2223 0.543 11:49:36.3 +22:23:58.1 11:49:40.5 +22:18:02.3 MACSJ1149+2223 regions
Year 3:
Abell S1063 (RXCJ2248.7-4431) 0.348 22:48:44.4 -44:31:48.5 22:49:17.7 -44:32:43.8 RXCJ2248-4431 regions
Abell 370 0.375 02:39:52.9 -01:34:36.5 02:40:13.4 -01:37:32.8 Abell 370 regions

These were selected primarily on their predicted lensing strength*, their low/moderate zodiacal and Galactic backgrounds, their observability with ALMA and Mauna Kea, and their observability with HST and Spitzer. We've also looked at their suitability for deep radio observations, and their existing multi-wavelength data observations.

(* Lensing strengths were calculated by Dan Coe, Johan Richard, and Adi Zitrin, based on existing HST data.)

The parallel blank field positions are constrained by the availability of HST guide stars, which permit > 30-day windows of fixed roll-angle observations with both ACS and WFC3 at both the cluster and blank field positions. From the available locations, the final parallel field location was based primarily upon the ability to obtain very deep, high quality imaging in both HST and Spitzer. Therefore the avoidance of bright stars which would cause scattered light, saturated columns, and persistence took precedence over the avoidance of extended cluster structures.

Frontier Fields Locations on the sky
Frontier Fields Locations
Cluster Candidate List