Hubble Space Telescope
Frontier Fields

The Frontier Fields Goals:

After considering valuable advice from the astronomical community and broad range of open questions in galaxy evolution, the committee has unanimously recommended a program of six deep fields centered on strong lensing galaxy clusters in parallel with six deep “blank fields”.

The key science goals of these twelve new frontier fields are:

• to reveal hitherto inaccessible populations of z = 5 - 10 galaxies that are 10 - 50 times fainter intrinsically than any presently known
• to solidify our understanding of the stellar masses and star formation histories of sub-L_* galaxies at the earliest times
• to provide the first statistically meaningful morphological characterization of star forming galaxies at z > 5
• to find z > 8 galaxies stretched out enough by cluster lensing to discern internal structure and/or magnified enough by cluster lensing for spectroscopic follow-up.

The full report and recommendations are here: SWG Report 2012

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. The targeted clusters and parallel blank field positions are currently being selected, and will be announced on this website in January prior to the HST Cycle 21 deadline. Proposers will be able to submit Cycle 21 archival and theory proposals to analyze data taken for this program.

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. The ACS filters will be F435W, F606W, F814W and the WFC3 filters will be F105W, F125W, F140W, and F160W for both the clusters and blank fields.

All data for this observing program will be nonproprietary and available immediately upon entry into the Mikulski Archive for Space Telescopes (typically within 24 hours of observation). As it has done for previous deep fields, STScI will create fully-calibrated high-level science products ready for scientific analysis by the astronomical community soon after the raw data are obtained. Information about those products and their schedule for creation and release will be posted on this webpage.

STScI recognizes the challenges involved in analyzing these data, particularly those associated with the cluster fields, and will be taking steps to provide an appropriate set of tools and information to enable broad community access. Preliminary (but high-quality) lensing and magnification maps of the Frontier Field clusters will be made available to the community prior to the Frontier Field observations through our call for Lensing Map Proposals.

Six Frontier Fields:

Our final fields are:

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