Resubmission for repeat of failed visit 03 of 47Tuc -77157577 ----- Attempting Submission 1 (Tue Aug 05 19:03:52 GMT 2025) ----- ----- Attempting Submission 2 (Wed Jan 28 19:49:51 GMT 2026) ----- Added other team Co-Is as is typical WFC3 IR Time-Dependent Sensitivity: Clusters A variety targets/techniques result in range of IR sensitivity loss estimates. For example, the IR grism flux monitor suggests losses of 0.12+/-0.01%/yr (G102) and 0.06+/-0.01%/yr(G141). The IR photometric monitor, however, shows no strong evidence of sensitivity loss in the IR imaging filters, but the repeatability is limited by systematic errors of +/-1%. Scanned images of M35 show marginal losses 0.065+/-0.01%/yr in F140W, but these data have a large scatter which may be related to detector preconditioning. Cluster observations allow for the measurement of many more stars. We continue the monitoring of the sensitivity of the WFC3/IR channel using relative photometry of the clusters M-4 and 47 Tuc, as performed in HST programs 16864, 16512, 17260, 17363 and 17683. This program serves to complement the sensitivity change slopes from the M35 scans, G102/G141 measurements, and standard star photometric monitoring. We observe the same targets as 17683 (M4 and 47 Tuc external fields) and use similar observation strategies, though some exposures were necessarily shortened due to the reduced gyro mode effects on orbital visibility length. As M4 was imaged twice in the previous cycle, we swap to observing 47 Tuc twice and M4 once to keep a roughly balanced cadence. These observations will help constrain the time dependent sensitivity change through 2025, as well as provide a rich dataset for examining other detector behaviors. Recent analysis of these data suggest losses of 0.12+/-0.01%/yr in F110W (M4) and 0.05+/-0.05%/yr in F160W (NGC104) These observations use a very similar observing strategy as seen in 17863. For the M4 visits, the two F110W exposures remain the same, however the second of the F160W exposures was shortened to fit within the shorter orbit. For 47 Tuc the dark exposure in the middle of the visit was shortened from NSAMP = 8 to NSAMP=7 to fit within the shortened orbit. The M4 visits consist of 4 exposures, starting with two F110W and ending with two F160W exposures. The F110W exposures will use the SPARS50 sample sequence with 14 samples. The F160W exposures will only use 13 and then 9 samples, due to the shorter orbital length due to RGM After each exposure POSTARGS of 2.5" will be applied, to mitigate self persistence. The 47 Tuc observations match the observing strategy from 17863 of alternating F160W exposures of the cluster with dark frames. Though the dark frames are unecessary for this monitoring, we keep them to specifically keep consistent detector conditions, to eliminate systematics due to observation strategy differences. However, in this cycle the penultimate dark is further shortened, to keep the same exposure times for the external images, so there is slight modification to the strategy overall. These observations use a very similar observing strategy as seen in 17863. For the M4 visits, the two F110W exposures remain the same, however the second of the F160W exposures was shortened to fit within the shorter orbit. For 47 Tuc the dark exposure in the middle of the visit was shortened from NSAMP = 8 to NSAMP=7 to fit within the shortened orbit. The M4 visits consist of 4 exposures, starting with two F110W and ending with two F160W exposures. The F110W exposures will use the SPARS50 sample sequence with 14 samples. The F160W exposures will only use 13 and then 9 samples, due to the shorter orbital length due to RGM After each exposure POSTARGS of 2.5" will be applied, to mitigate self persistence. The 47 Tuc observations match the observing strategy from 13563 of alternating F160W exposures of the cluster with dark frames. Though the dark frames are unecessary for this monitoring, we keep them to specifically keep consistent detector conditions, to eliminate systematics due to observation strategy differences. 0 false false false RESTRICTED CALIBRATION DETECTOR LINEARITY TEST NGC104 J2000 STELLAR CLUSTER GLOBULAR CLUSTER J2000 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17963 :visit-id "01" :proposal-version -1 :trans-version "20250624" :date "29-Jul-2025 14:56:28.0" :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 1566800 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17963 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17963 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2319 :al-overhead-at-end 0 :internal-dur-at-end 690 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3121 :pcs-gap 0 ) true 1 0 Designed to just saturate V=20 stars. The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. 1770505879000 280.0 (Tic-Visit :proposal-id 17963 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "29-Jul-2025 14:56:29.0" :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 940064 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17963 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17963 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2561 :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 2983 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. 1769032193000 113.0 (Tic-Visit :proposal-id 17963 :visit-id "03" :proposal-version -1 :trans-version "20250624" :date "29-Jul-2025 14:56:30.0" :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 1566800 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17963 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17963 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2319 :al-overhead-at-end 0 :internal-dur-at-end 690 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3121 :pcs-gap 0 ) true 1 0 Designed to just saturate V=20 stars. The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17963 :visit-id "A3" :proposal-version -1 :trans-version "20250929" :date "28-Jan-2026 14:46:22.0" :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 1566800 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17963 :visit-id "A3" :obset-id "A3" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17963 :visit-id "A3" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2319 :al-overhead-at-end 0 :internal-dur-at-end 690 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3121 :pcs-gap 0 ) false 1 0 Designed to just saturate V=20 stars.