0 Assigned ID: 72 ----- Attempting Submission 1 (Tue Apr 07 04:59:02 GMT 2015) ----- HST Phase I Proposal 72 (Cycle23_HFF_AR.apt) successfully submitted. Receipt: # 72-1 ----- Attempting Submission 2 (Wed Apr 08 03:40:19 GMT 2015) ----- HST Phase I Proposal 72 (Cycle23_HFF_AR.apt) successfully submitted. Receipt: # 72-2 ----- Attempting Submission 3 (Fri Apr 10 02:05:37 GMT 2015) ----- HST Phase I Proposal 72 (Cycle23_HFF_AR.apt) successfully submitted. Receipt: # 72-3 ----- Attempting Submission 4 (Fri Apr 10 14:45:51 GMT 2015) ----- HST Phase I Proposal 72 (Cycle23_HFF_AR.apt) successfully submitted. Receipt: # 72-4 ----- Attempting Submission 5 (Fri Apr 10 22:44:49 GMT 2015) ----- Cluster-scale gravitational lenses act as cosmic telescopes, enabling the study of otherwise unobservable galaxies. To use these cosmic telescopes we need robustly derived magnification maps and error analyses. They are essential to understand the systematic errors present in such investigations. While the STScI special call for proposals to get magnification information for Hubble Frontier Fields (HFF) provided the first-order maps, this proposal will add (i) ultra deep HFF data, (ii) HST and Keck spectroscopy, (iii) improved weak lensing treatment, and (iv) flexion analysis to produce a factor of 2 improvement in precision of the magnification estimates for the HFF clusters. The improved magnification models developed here will result in a significant improvement of our knowledge about the z>~7 Universe. In particular, reaching fainter luminosities to higher precision and adding Spitzer data, with this proposal we will study the role that these galaxies play in galaxy formation models (by accurately measuring stellar masses, ages and star formation rates) and their contribution to the bulk of ionizing photons necessary to drive reionization. These tasks are made possible by the power of cosmic telescopes, the vast amounts of HST, Spitzer, and ground based data acquired in these fields, and our previously demonstrated techniques for accurately quantifying magnification of cosmic telescopes and stellar properties of z>~7 galaxies. All the lens models as well as Spitzer imaging and photometry will be made available to the community, making this proposal of lasting legacy value. COSMOLOGY 0 Legacy false false false false false SUPPORTED