16668( 4) - 29-Jul-2021 16:45:30 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16668 Version: 4 Check-in Time: 29-Jul-2021 16:45:30 STScI Edit Number: 0 Title Monitoring Earendel, the Lensed z~6 Star ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Dan Coe Space Telescope Science Institute - ESA - Y JWST CoI: Brian Welch The Johns Hopkins University Y CoI: Dr. Jose M. Diego Instituto de Fisica de Cantabria N CoI: Dr. Adi Zitrin Ben Gurion University of the Negev N CoI: Dr. Patrick Kelly University of Minnesota - Twin Cities N CoI: Dr. Erik Zackrisson Uppsala Astronomical Observatory N CoI: Dr. Selma E. de Mink Max Planck Institute for Astrophysics N CoI: Frank Timmes Arizona State University N CoI: Prof. Rogier A. Windhorst Arizona State University N CoI: Prof. Keren Sharon University of Michigan N CoI: Dr. Guillaume Mahler Durham Univ. N CoI: Prof. Masamune Oguri Institute for Physics and Mathematics of N the Universe CoI: Yolanda Jimenez-Teja Instituto de Astrofisica de Andalucia N (IAA) CoI: Mrs. Paola Dimauro Observatorio Nacional N CoI: Dr. Michael Florian University of Arizona N CoI: Dr. Jane R. Rigby NASA Goddard Space Flight Center N CoI: Prof. Marusa Bradac University of California - Davis N CoI: Victoria Strait University of California - Davis N CoI: Ebraheem Farag Arizona State University N CoI: Dr. Steve Rodney University of South Carolina N CoI: Kyle O'Connor University of South Carolina Research N Foundation CoI: Dr. Louis-Gregory Strolger Space Telescope Science Institute N CoI: Mr. Anton Filip Vikaeus Uppsala Astronomical Observatory N CoI: Ana Acebron Ben Gurion University of the Negev N CoI: Dr. Larry Bradley Space Telescope Science Institute N CoI: Roberto Avila Space Telescope Science Institute N CoI: Prof. Brenda Louise Frye University of Arizona N ------------------------------------------------------------------------------------ Abstract Three strongly magnified individual stars have been discovered in z~1 galaxies thanks to temporary boosts from microlensing. All were discovered as transient events that have since faded. Now a more persistent and distant lensed star has been discovered at z~6, named "Earendel" ("morning light"). Its extremely high magnification has persisted for 3.5 years between HST observations, consistent with microlensing simulations of this object. But HST monitoring of the z~1 stars revealed things weren't always as they seemed. Here we propose the first repeat monitoring of Earendel in the same WFC3/IR filter, 16668( 4) - 29-Jul-2021 16:45:30 - [ 2] with 4 more epochs F110W imaging. These data will yield Earendel's baseline flux to better constrain its magnification, and thus luminosity and mass. Current HST data suggest it is likely very massive > 50 M_sun. And at z~6, it is likely low metallicity < 0.2 Z_sun. Very massive low metallicity stars are extremely rare in the local group and thus hard to study locally. Such stars are the likely progenitors of ~30 M_sun black holes measured by LIGO gravitational wave detections. But models of their evolutionary tracks are highly uncertain. Remarkably, this isolated z~6 star may offer the best opportunity to pinpoint the giant branch of a low metallicity massive star. Approved JWST GO observations will constrain the star's temperature, putting a z~6 star on the H-R diagram with a luminosity (and mass) precision significantly improved by this HST proposal. To support the various communities interested in these results, we waive any proprietary period to the data, in the same spirit as the previous HST observations and approved JWST observations of this exciting target. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain 4 orbits of WFC3/IR F110W imaging of WHL0137-08, aligned with the previous HST imaging of that galaxy cluster core. We request 4 separate visits, each 1 orbit long, separated by 3 or more months. *** Longer time baselines are preferable: Visit #1 as early as possible in Cycle 29 and Visit #4 as late as needed to accommodate scheduling other programs. Within each orbit, we will obtain 4 images in a single filter, using small dithers to optimally sample the PSF and ultimately improve the spatial resolution of the stacked drizzled images. Between orbits / epochs, we will perform a larger dither (and/or different roll angle) to cover the WFC3/IR "death star" and other artifacts (IR blobs), as well as the ACS chip gap in parallel. Special Requirements: 1) 4 epochs (1 orbit per epoch), each 3 or more months apart (e.g., Oct, Feb, Jun, Sept.) 2) Low backgrounds when possible 3) Position Angle to overlap parallel imaging with existing HST imaging when possible We do not request mitigation of helium Earthshine, which is rare and not expected to impact a significant fraction of our data. We prefer to perform all dithers in the same orbit for optimal pixel sampling rather than splitting orbits to avoid helium. ------------------------------------------------------------------------------------ 16668( 4) - 29-Jul-2021 16:45:30 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 WHL0137-08 CLUSTER OF GALAXIES, RA=01H37M25.0000S, J2000 V = 18 GRAVITATIONAL LENS, DEC=-08D27'25.00" RICH CLUSTER Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 2 EARENDEL STAR, SUPERGIANT O RA=01H37M23.2320S, J2000 V = 18 DEC=-08D27'52.20" Reference Frame: ICRS Extended: NO Comments: Our primary target, included for visual confirmation that it will be well observed in all epochs. ------------------------------------------------------------------------------------------------------------------------------------ 16668( 4) - 29-Jul-2021 16:45:30 - [ 4] Visit: 11 (1 IR/F110W-ACS/F814W) Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=12 1 DEF PAR 2 WITH 1 CUM (552.937 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY ACS/WFC ACCUM WFCENTER F814W 1 497 S see below (375 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 0.542, 0.182; CUM (652.938 PAR 4 WITH 3 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F814W 1 557 S (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 0.339, 0.485; CUM (652.938 PAR 6 WITH 5 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY ACS/WFC ACCUM WFCENTER F814W 1 557 S see below (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF POS TARG -0.203, 0.303; CUM (602.938 PAR 8 WITH 7 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F814W 1 507 S see below (507 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ WHL0137-08 1 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 375.0 S WHL0137-08 3 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM 16668( 4) - 29-Jul-2021 16:45:30 - [ 5] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ANY 4 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A WHL0137-08 5 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 6 ACS/WFC ACCUM WFCENTER F814W none none none none 1 557.0 S WHL0137-08 7 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 8 ACS/WFC ACCUM WFCENTER F814W none none none none 1 507.0 S 16668( 4) - 29-Jul-2021 16:45:30 - [ 6] Visit: 22 (2 IR/F110W-ACS/F435W) Visit Requirements: ORIENT 50D TO 75 D; ORIENT 215D TO 240 D; AFTER 11 BY 60 D TO 300 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=12 1 DEF POS TARG 7.317, 0.908; CUM (552.937 PAR 2 WITH 1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY ACS/WFC ACCUM WFCENTER F435W 1 497 S see below (375 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 7.859, 1.090; CUM (652.938 PAR 4 WITH 3 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F435W 1 557 S (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 7.656, 1.393; CUM (652.938 PAR 6 WITH 5 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY ACS/WFC ACCUM WFCENTER F435W 1 557 S see below (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF POS TARG 7.114, 1.211; CUM (602.938 PAR 8 WITH 7 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F435W 1 500 S see below (507 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ WHL0137-08 1 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 2 ACS/WFC ACCUM WFCENTER F435W none none none none 1 375.0 S WHL0137-08 3 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM 16668( 4) - 29-Jul-2021 16:45:30 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ANY 4 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A WHL0137-08 5 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 6 ACS/WFC ACCUM WFCENTER F435W none none none none 1 557.0 S WHL0137-08 7 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 8 ACS/WFC ACCUM WFCENTER F435W none none none none 1 507.0 S 16668( 4) - 29-Jul-2021 16:45:30 - [ 8] Visit: 33 (3 IR/F110W-ACS/F814W) Visit Requirements: ORIENT 215D TO 240 D; ORIENT 50D TO 75 D; AFTER 11 BY 150 D TO 450 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=12 1 DEF PAR 2 WITH 1 CUM (552.937 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY ACS/WFC ACCUM WFCENTER F814W 1 497 S see below (375 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 0.542, 0.182; CUM (652.938 PAR 4 WITH 3 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F814W 1 557 S (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 0.339, 0.485; CUM (652.938 PAR 6 WITH 5 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY ACS/WFC ACCUM WFCENTER F814W 1 557 S see below (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF POS TARG -0.203, 0.303; CUM (602.938 PAR 8 WITH 7 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F814W 1 507 S see below (507 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ WHL0137-08 1 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 2 ACS/WFC ACCUM WFCENTER F814W none none none none 1 375.0 S WHL0137-08 3 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM 16668( 4) - 29-Jul-2021 16:45:30 - [ 9] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ANY 4 ACS/WFC ACCUM WFCENTER F814W none none none none 1 N/A WHL0137-08 5 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 6 ACS/WFC ACCUM WFCENTER F814W none none none none 1 557.0 S WHL0137-08 7 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 8 ACS/WFC ACCUM WFCENTER F814W none none none none 1 507.0 S 16668( 4) - 29-Jul-2021 16:45:30 - [ 10] Visit: 44 (4 IR/F110W-ACS/F606W) Visit Requirements: ORIENT 50D TO 75 D; ORIENT 215D TO 240 D; AFTER 11 BY 300 D TO 750 D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=12 1 DEF POS TARG 7.317, 0.908; CUM (552.937 PAR 2 WITH 1 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY ACS/WFC ACCUM WFCENTER F606W 1 497 S see below (375 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 7.859, 1.090; CUM (652.938 PAR 4 WITH 3 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F606W 1 557 S (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG 7.656, 1.393; CUM (652.938 PAR 6 WITH 5 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ANY ACS/WFC ACCUM WFCENTER F606W 1 557 S see below (557 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 WHL0137-08 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF POS TARG 7.114, 1.211; CUM (602.938 PAR 8 WITH 7 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F606W 1 500 S see below (507 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ WHL0137-08 1 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 2 ACS/WFC ACCUM WFCENTER F606W none none none none 1 375.0 S WHL0137-08 3 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM 16668( 4) - 29-Jul-2021 16:45:30 - [ 11] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ ANY 4 ACS/WFC ACCUM WFCENTER F606W none none none none 1 N/A WHL0137-08 5 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 6 ACS/WFC ACCUM WFCENTER F606W none none none none 1 557.0 S WHL0137-08 7 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 8 ACS/WFC ACCUM WFCENTER F606W none none none none 1 507.0 S 16668( 4) - 29-Jul-2021 16:45:30 - [ 12] Summary Form for Proposal 16668 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX, WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=12, NSAMP=13, NSAMP=14, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 11 BY 150 D TO 450 D, AFTER 11 BY 300 D TO 750 D, AFTER 11 BY 60 D TO 300 D, ORIENT 215D TO 240 D, ORIENT 50D TO 75 D, PAR 2 WITH 1, PAR 4 WITH 3, PAR 6 WITH 5, PAR 8 WITH 7, POS TARG -0.203, 0.303, POS TARG 0.339, 0.485, POS TARG 0.542, 0.182, POS TARG 7.114, 1.211, POS TARG 7.317, 0.908, POS TARG 7.656, 1.393, POS TARG 7.859, 1.090 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F435W, F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ANY, WHL0137-08 ------------------------------------------------------------------------------------------------------------------------------------