Final version 2 -1570894688 Assigned ID: 668 ----- Attempting Submission 1 (Fri Apr 07 17:24:09 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) successfully submitted. Receipt: # 668-1 ----- Attempting Submission 2 (Fri Apr 07 22:16:43 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) successfully submitted. Receipt: # 668-2 ----- Attempting Submission 3 (Fri Apr 07 22:50:02 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) failed submission. ----- Attempting Submission 4 (Fri Apr 07 22:51:11 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) failed submission. ----- Attempting Submission 5 (Fri Apr 07 22:53:40 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) successfully submitted. Receipt: # 668-5 ----- Attempting Submission 6 (Fri Apr 07 23:18:09 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) failed submission. ----- Attempting Submission 7 (Fri Apr 07 23:18:28 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) failed submission. ----- Attempting Submission 8 (Fri Apr 07 23:19:29 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) failed submission. ----- Attempting Submission 9 (Fri Apr 07 23:20:00 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) failed submission. ----- Attempting Submission 10 (Fri Apr 07 23:21:20 GMT 2017) ----- HST Phase I Proposal 668 (DraftProposal.apt) failed submission. ----- Attempting Submission 11 (Fri Apr 07 23:24:07 GMT 2017) ----- HST Phase I Proposal 668 (NearFinal.apt) failed submission. ----- Attempting Submission 12 (Fri Apr 07 23:25:23 GMT 2017) ----- HST Phase I Proposal 668 (NearFinal.apt) successfully submitted. Receipt: # 668-12 ----- Attempting Submission 13 (Sat Apr 08 00:12:22 GMT 2017) ----- Substantial investment is being made in space- and ground-based missions with the goal of revealing the nature of the observed cosmic acceleration. This is one of the most important unsolved problems in cosmology today. We propose here to constrain the evolution of the Hubble parameter [H(z)] between 1.3 < z < 2, using the cosmic chronometer method, based on differential age measurements for passively evolving galaxies. Existing WFC3-IR G102 and G141 grisms data obtained by the WISP, 3D-HST+AGHAST, FIGS, and CLEAR surveys will yield a sample of ~140 suitable standard clocks, expanding existing samples by a factor of five. These additional data will enable us to improve existing constraints on the evolution of H at high redshift, and insodoing to better understand the fundamental nature of dark energy. Cosmology Galaxies and the IGM 0 Regular false false false SUPPORTED