0 Assigned ID: 6147 ----- Attempting Submission 1 (Mon Apr 07 23:04:25 GMT 2025) ----- Adjusted readout sequence following suggestions from the contact scientist. Using STEP50 and NSAMP=10 now. Ungrouped visits to fix the SEQ NON-INT issue. 1385023466 ----- Attempting Submission 1 (Fri Aug 01 19:54:33 GMT 2025) ----- ----- Attempting Submission 2 (Wed Oct 01 19:57:33 GMT 2025) ----- HST Phase II Proposal 18027 successfully submitted. Receipt: # 18027-2 ----- Attempting Submission 3 (Wed Oct 01 23:16:52 GMT 2025) ----- Securing the HST Surface Brightness Fluctuation Legacy with a Robust JWST Calibration Addressing the "Hubble tension" is a top priority for JWST, and several programs have been awarded time to construct a completely independent distance ladder based on old populations in elliptical galaxies instead of Cepheid variable stars in spiral galaxies. In particular, tip of the red giant branch (TRGB) stars have been measured in 14 early-type galaxies with JWST for the purpose of calibrating the surface brightness fluctuation (SBF) method. However, thus far only 8 of these galaxies have SBF measurements with HST WFC3/IR. We propose to complete the calibration linkage between HST and JWST by using HST WFC3/IR to observe the remaining 6 galaxies with established JWST TRGB distances. The result will be a higher precision zero point for the HST SBF sample, expanding the calibration from 8 to 14 galaxies. The TRGB calibration of SBF decouples the large archival sample of over 230 HST IR SBF measurements from the Cepheid-SN Ia ladder. The HST SBF sample, spanning the sky and extending to 100 Mpc, provides an independent estimate of the Hubble constant based solely on old stellar populations. Imaging observations of six elliptical galaxies closer than 20 Mpc in WFC3/IR basic imaging mode, using the default dither pattern with N=4 steps to correct for bad pixels. One orbit per galaxy. Two filters will be used (F110W and F160W) with observations split into four dither positions in each filter. The readout mode of SPARS50 and NSAMP=6 provides 1012 sec in each filter. Team Expertise: Joseph Jensen (PI, Utah Valley University) will lead the program and be responsible for overseeing the measurement of SBF distances. Jensen has extensive experience with IR SBF on HST, starting with NICMOS and now continuing with WFC3/IR analyzing data from 11 different HST programs. John Blakeslee (NOIRLab) has extensive experience with measuring optical and IR SBF using HST, particularly with the ACS. He has extensive experience with stellar population modeling, globular cluster populations, and galaxy evolution. Michele Cantiello (INAF) is an expert in surface brightness fluctuation measurement, stellar population modeling, and photometry of GC populations. He will work on the SBF measurements and cross-calibration of the SBF technique. R. Brent Tully (U. Hawaii Institute for Astronomy) leads the Cosmicflows program of galaxy distances with multiple methodologies. He will be responsible for integration of the new re-calibrated SBF distances with Cosmicflows. He is the curator of the Extragalactic Distance Database. Gagandeep Anand (STScI) has expertise in HST photometry and measuring distances using the TRGB method, and is responsible for the distance moduli used in this project. Ehsan Kourkchi (U. Hawaii Institute for Astronomy) has worked for the past few years on both Cosmicflows and writing python code for analyzing SBF data to derive distances. No generative AI tools were used in the preparation of this proposal. Galaxies 6 false false false false false false SUPPORTED GALAXY ELLIPTICAL YES This object was generated by the targetselector and retrieved from the NED database. J2000 J2000 J=9.1 GALAXY ELLIPTICAL YES This object was generated by the targetselector and retrieved from the NED database. NGC-4374 J2000 J2000 GALAXY ELLIPTICAL YES This object was generated by the targetselector and retrieved from the NED database. NGC-4406 J2000 J2000 GALAXY ELLIPTICAL YES This object was generated by the targetselector and retrieved from the NED database. NGC-4621 J2000 J2000 GALAXY ELLIPTICAL This object was generated by the targetselector and retrieved from the NED database. NGC-4486 J2000 J2000 GALAXY ELLIPTICAL YES This object was generated by the targetselector and retrieved from the NED database. NGC-3379 J2000 J2000 WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W POS-TARG DITHER DITHER 4 5.183 WFC3-IR-DITHER-BOX-MIN false 74.653 true 0.365 0.572 4 41.859 POS-TARG WFC3-IR-DITHER-BLOB 18.528 1 false The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18027 :visit-id "01" :proposal-version -1 :trans-version "20250624" :date "01-Oct-2025 17:16:37.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1532000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18027 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18027 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2524 :al-overhead-at-end 0 :internal-dur-at-end 709 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2928 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18027 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "01-Oct-2025 17:16:37.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1532000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18027 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18027 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2524 :al-overhead-at-end 0 :internal-dur-at-end 709 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2909 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18027 :visit-id "03" :proposal-version -1 :trans-version "20250624" :date "01-Oct-2025 17:16:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1532000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18027 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18027 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2524 :al-overhead-at-end 0 :internal-dur-at-end 709 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2909 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18027 :visit-id "04" :proposal-version -1 :trans-version "20250624" :date "01-Oct-2025 17:16:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1532000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18027 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18027 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2524 :al-overhead-at-end 0 :internal-dur-at-end 709 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2909 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18027 :visit-id "05" :proposal-version -1 :trans-version "20250624" :date "01-Oct-2025 17:16:38.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1532000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18027 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18027 :visit-id "05" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2524 :al-overhead-at-end 0 :internal-dur-at-end 709 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2909 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18027 :visit-id "06" :proposal-version -1 :trans-version "20250624" :date "01-Oct-2025 17:14:10.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1532000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18027 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18027 :visit-id "06" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2524 :al-overhead-at-end 0 :internal-dur-at-end 709 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2909 :pcs-gap 0 ) false 1 0