17911( 4) - 11-Mar-2025 17:50:16 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17911 Version: 4 Check-in Time: 11-Mar-2025 17:50:16 STScI Edit Number: 1 Title Building the Last Bridge Between the PHAT & PHATTER Surveys and Carbon Star Cosmology ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Siyang Li The Johns Hopkins University Y CoI: Dr. Adam Riess The Johns Hopkins University N CoI: Dr. Stefano Casertano Space Telescope Science Institute N CoI: Dr. Gagandeep Singh Anand Space Telescope Science Institute N CoI: Dr. Caroline Huang Smithsonian Institution Astrophysical N Observatory CoI: Dr. Wenlong Yuan The Johns Hopkins University N ------------------------------------------------------------------------------------ Abstract The Hubble Tension refers to a >5 sigma difference between local and cosmological measurements of the present expansion rate of our universe, the Hubble constant (H0). This tension hints at the possibility of undiscovered physics undermining the canonical standard model of our universe. Probing the Hubble Tension necessitates intense scrutiny of the Cepheid-based distance ladder, which currently provides the strongest constraints on direct H0 measurements. Possibly the most powerful approach to test systematics in the Cepheid-based steps of the distance ladder is to develop and use independent standard candles to measure distances to galaxies. To date, agreement with another candle, the tip of the red giant branch (TRGB), has been elusive. The J-region Asymptotic Giant Branch (JAGB) is a new standard candle that can provide independent relative distances between nearby systems, as well as crosscheck Cepheid systematics at > 30 Mpc. The Panchromatic Hubble Andromeda Treasury (PHAT) and PHAT Triangulum Extended Region (PHATTER) were HST multi-cycle programs that mapped a third of the star forming disk in M31 and central ~0.1 deg2 region of M33 and are unequivocally the best testing grounds for characterizing and standardizing the JAGB via cross calibration with other standard candles. However, there currently exists no F110W observations of the outer disk in NGC 4258 that can be used to measure JAGB distances with PHAT & PHATTER. We propose to fill in this gap and observe the outer disk of NGC 4258 in the HST WFC3/IR F110W filter. This cycle is the last that will enable tying the PHAT & PHATTER legacies to Carbon star cosmology. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program will observe multipel fields in NGC 4258 in the WFC3 F110W filter to observe JAGB stars. These fields will overlap with one of the existing NGC 4258 fields, which will provide the F814W observations needed to differentiate these JAGB stars via color cuts. ------------------------------------------------------------------------------------ 17911( 4) - 11-Mar-2025 17:50:16 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M-106 GALAXY, SPIRAL RA=12H18M34.0068S, J2000 V = 8.41 DEC=+47D14'55.68" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17911( 4) - 11-Mar-2025 17:50:16 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type LINE WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER DITHER Number_Of_Points 3 4 Point_Spacing 1.908 1.716 Line_Spacing 1.095 Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 41.788 18.528 Angle_Between_Sides 74.653 Center_Pattern NO NO ------------------------------------------------------------------------------------------------------------------------------------ 17911( 4) - 11-Mar-2025 17:50:16 - [ 4] Visit: 01 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 M-106 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS25, NSAMP=15 1 DEF POS TARG CUM (4235.274 -62.56638000000001, S) -55.37128500000001; GS ACQ SCENARIO BASE1O3; PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 3 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 4 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 4 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 1 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 2 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 4 none none 2 N/A CUM 17911( 4) - 11-Mar-2025 17:50:16 - [ 5] Visit: 02 Visit Requirements: SAME ORIENT AS 01 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 M-106 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS25, NSAMP=15 1 DEF POS TARG CUM (4235.274 62.56638000000001, S) -55.37128500000001; GS ACQ SCENARIO BASE1O3; PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 3 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 4 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 4 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 1 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 2 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 4 none none 2 N/A CUM 17911( 4) - 11-Mar-2025 17:50:16 - [ 6] Visit: 03 Visit Requirements: SAME ORIENT AS 01 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 M-106 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS25, NSAMP=15 1 DEF POS TARG CUM (4235.274 -62.56638000000001, S) 55.37128499999999; GS ACQ SCENARIO BASE1O3; PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 3 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 4 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 4 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 1 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 2 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 4 none none 2 N/A CUM 17911( 4) - 11-Mar-2025 17:50:16 - [ 7] Visit: 04 Visit Requirements: SAME ORIENT AS 01 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 M-106 WFC3/IR MULTIAC IR-FIX F110W SAMP-SEQ=SPARS25, NSAMP=15 1 DEF POS TARG CUM (4235.274 62.56638000000001, S) 55.37128499999999; GS ACQ SCENARIO ONEB1O3; PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 3 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 1 4 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 1 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 2 none none 1 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 2 4 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 1 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 2 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 3 none none 2 N/A CUM M-106 1 WFC3/IR MULTIAC IR-FIX F110W 3 4 none none 2 N/A CUM 17911( 4) - 11-Mar-2025 17:50:16 - [ 8] Summary Form for Proposal 17911 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=15, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GS ACQ SCENARIO BASE1O3, GS ACQ SCENARIO ONEB1O3, PATTERN 2 1, POS TARG -62.56638000000001, -55.37128500000001, POS TARG -62.56638000000001, 55.37128499999999, POS TARG 62.56638000000001, -55.37128500000001, POS TARG 62.56638000000001, 55.37128499999999, SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M-106 ------------------------------------------------------------------------------------------------------------------------------------