0 Assigned ID: 254 ----- Attempting Submission 1 (Thu Apr 06 17:11:35 GMT 2017) ----- HST Phase I Proposal 254 (APTKaliraiUVWDs.apt) successfully submitted. Receipt: # 254-1 ----- Attempting Submission 2 (Fri Apr 07 18:20:29 GMT 2017) ----- HST Phase I Proposal 254 (APTKaliraiUVWDs.apt) successfully submitted. Receipt: # 254-2 Resubmitted to account for orbital overruns for Visit 01 (due to ongoing gyro issues, operational change made to increase the amount of time needed for guide star reacquisition) 9583308 ----- Attempting Submission 1 (Wed Jul 19 18:53:42 GMT 2017) ----- ----- Attempting Submission 2 (Tue Dec 18 21:17:32 GMT 2018) ----- Dr. A. Riess was added to the proposal by GMS for admin PI reasons. This has been approved. We propose a 5 orbit HST program to acquire UV imaging at the center of the ancient, metal-poor globular cluster NGC 6341 (M92). Our program is designed to achieve two science goals with a single data set, 1.) to directly measure the diffusion of stars through the massive cluster's core, 2.) to pinpoint the phase of post main-sequence evolution at which [Fe/H] = -2.3 stars lose their mass. Our novel technique will achieve these goals by using the full power of WFC3's exquisite UV sensitivity at <0.3 microns combined with its high spatial resolution. We will uncover ~1000 newly-formed white dwarfs in the center of M92 and track how their spatial distribution changes as they get "older" on the cooling sequence. Having just experienced significant mass loss, the youngest remnants with ages <10s of Myr will still be moving slowly like their 0.8 Msun progenitors, whereas the "older" remnants with t_cool > 100s Myr will be fully relaxed. Using the methodology we developed and successfully applied to 47 Tuc (Heyl et al. 2015a; 2015b), we will "watch" this dynamical evolution to measure the diffusion coefficient due to gravitational relaxation in the cluster's core and the past timing of stellar mass loss that was responsible for the current cluster mass segregation profile. M92 is the ideal target for this study as it complements our existing study of the relatively metal-rich cluster 47 Tuc; it has an extremely low metallicity of [Fe/H] = -2.3, very low foreground reddening (E(B-V) = 0.02), moderate concentration index, and a theoretically-expected relaxation timescale in its core of 90 Myr, which nicely splits the young and old white dwarfs that can be observed with Hubble. This is a 5 orbit program that we would like to execute in one block. The primary camera is HST/WFC3/UVIS and the parallel camera is ACS. We are using two filters in both instrument. The observations are sequenced to obtain 4 integrations on both cameras in each orbit, hiding all of the buffer dumps. This includes short integrations on WFC3/UVIS to mitigate saturation of bright sources. All observations are dithered. There are also orient constraints to line up the observations with one of the archival data sets from GO-13297 that have to be coadded to our data. Stellar Populations Stellar Physics 6 false false true false false false false SUPPORTED STELLAR CLUSTER GLOBULAR CLUSTER This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 WFC3/UVIS Imaging No No F225W WFC3/UVIS Imaging No No F275W ACS/WFC Imaging No No F435W ACS/WFC Imaging No No F555W 1545147599705 /Users/correnti/Proposal/HST/cycle25/CoI_Proposals/OP-cache/15173-v01.xml The scheduling data was generated by CASM 26.2.2. CASM was run in Phase II mode. 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