Hubble Boldly Goes: The Frontier Fields Program

The Cycle 21 program

As announced in the Cycle 21 Call for Proposals, the community was encouraged to submit archival proposals to analyze HFF data, develop supporting theoretical tools, and/or submit observing proposals to obtain supplementary data. Submitted proposals will be reviewed in competition with all other Cycle 21 proposals by the Cycle-21 Time Allocation Committee. By policy, Institute staff members on the core implementation team may not serve as principal investigators on Cycle 21 proposals related to the HFF program, nor could they apply for funding as co-investigators on any such proposals.

The two clusters selected for observation in Cycle 21 are Abell 2744 and MACSJ0416.1-2403 (Figure 4). Abell 2744, also known as Pandora’s Cluster, is a complex, massive system lying at redshift z = 0.308. The cluster has previous Hubble observations (PI R. Dupke: GO 11689) and has been identified as the product of a major merger involving up to four ~1014 MSun separate clusters. Thirty to forty lensed images of background galaxies have already been identified in the system (Merten et al. 2011). To date, this cluster has only ACS observations, and the WFC3-IR imaging offers great potential for discovery. The HFF observations will focus on the southeast component, which is the most massive and well matched in angular size to the WFC3-IR field of view.

The second cluster scheduled for observation in Cycle 21, MACSJ0416.1-2403, lies at redshift z = 0.396 and has also been identified as a merging cluster (Mann & Ebeling 2012). Targeted by the CLASH Multi-Cycle Treasury program, multiply lensed images of more than 20 background galaxies are already known (Zitrin et al. 2013). Both clusters have initial measurements of critical lensing curves and magnification maps, and both can be expected to provide high-magnification sampling of the high-redshift universe. The first HFF observations of both clusters are likely to be obtained in the late fall of this year.


The extensive investment of Hubble resources in deep imaging programs over the last two decades has pushed the high-redshift frontier from z ~ 2 to beyond z = 10. At the same time, the non-proprietary nature of DDT and Treasury programs has ensured rapid access to these data for the entire astronomical community, maximizing the scientific exploitation of the observations. The HFF program represents a continuation of this philosophy, and lays the foundations for future such programs with the James Webb Space Telescope.


Merten, J., et al. 2011, MNRAS, 417, 333
Schlegel, D. J., Finkbeiner, D. P., Davis, M., 1998, ApJ, 500, 525
Zheng, W., et al. 2012, Nature, 489, 406
Zitrin, A., et al. 2013, ApJ, 762, L30

Deep Field Surveys

HDFHubble Deep Field
HDF–SHubble Deep Field-South
GOODSGreat Observatories Origins Deep Survey
HUDFHubble Ultra-Deep Field
COSMOSCosmic Evolution Survey
HUDF09Hubble Ultra-Deep Field 2009
CANDELSCosmic Assembly Near-infrared Deep Extragalactic Legacy Survey
CLASHCluster Lensing And Supernova survey with Hubble
HUDF12Hubble Ultra-Deep Field 2012
CDF–SChandra Deep Field–South
HFFHubble Frontier Fields