17683( 5) - 28-Oct-2025 19:10:27 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17683 Version: 5 Check-in Time: 28-Oct-2025 19:10:27 STScI Edit Number: 1 Title WFC3 IR Time-Dependent Sensitivity: Clusters ------------------------------------------------------------------------------------ Type Cycle CAL/WFC3 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Varun Bajaj Space Telescope Science Institute Y CoI: Ky Huynh Space Telescope Science Institute Y CoI: Ms. Jennifer Mack Space Telescope Science Institute Y ------------------------------------------------------------------------------------ Abstract 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, and 17363. 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 17260 (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 47 Tuc was imaged twice in the previous cycle, we swap to observing M4 twice and 47 Tuc 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. ------------------------------------------------------------------------------------ Observations Description ------------------------ These observations use a very similar observing strategy as seen in 17260 as well as 17363. 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 = 15 to NSAMP=8 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 10 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. ------------------------------------------------------------------------------------ 17683( 5) - 28-Oct-2025 19:10:27 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC CALIBRATION, DETECTOR RA=00H22M27.8446S +/- 0.1", J2000 V = 22.0 LINEARITY TEST DEC=-72D04'4.75" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 3 M-4 STELLAR CLUSTER, RA=16H23M41.7160S, J2000 V = 5.9 GLOBULAR CLUSTER DEC=-26D30'19.01" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 17683( 5) - 28-Oct-2025 19:10:27 - [ 3] Visit: 01 (47Tuc Rolled) Visit Requirements: ORIENT 310D TO 318 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 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS25, NSAMP=13 1 DEF GS ACQ SCENARIO BASE1O3 CUM (302.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS10, NSAMP=10 1 DEF CUM (92.941 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS50, NSAMP=15 1 DEF CUM (702.939 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS25, NSAMP=15 1 DEF CUM (352.94 S) Comments: Designed to just saturate V=20 stars. ------------------------------------------------------------------------------------------------------------------------------------ 5 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS50, NSAMP=8 1 DEF CUM (352.935 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS10, NSAMP=10 1 DEF CUM (92.941 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS25, NSAMP=13 1 DEF POS TARG 4, 4 CUM (302.938 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 | ------------------------------------------------------------------------------------------------------------------------------------ DARK 1 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 47TUC 2 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM DARK 3 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 47TUC 4 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM DARK 5 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 17683( 5) - 28-Oct-2025 19:10:27 - [ 4] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 47TUC 6 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM 47TUC 7 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM 17683( 5) - 28-Oct-2025 19:10:27 - [ 5] Visit: 02 (M-4) Visit Requirements: ORIENT 280D TO 282 D; BETWEEN 01-JAN-2025:00:00:00 AND 15-MAR-2025:00:00:00 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-4 WFC3/IR MULTIAC IR-UVIS-F F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG -5, 5 CUM IX (652.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 M-4 WFC3/IR MULTIAC IR-UVIS-F F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG -2.5, 2.5 CUM IX (652.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 M-4 WFC3/IR MULTIAC IR-UVIS-F F160W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF POS TARG 0, 0 CUM IX (602.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 M-4 WFC3/IR MULTIAC IR-UVIS-F F160W SAMP-SEQ=SPARS50, NSAMP=10 1 DEF POS TARG -7.5, 7.5 CUM IX (452.936 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-4 1 WFC3/IR MULTIAC IR-UVIS- F110W none none none none 1 N/A CUM FIX M-4 2 WFC3/IR MULTIAC IR-UVIS- F110W none none none none 1 N/A CUM FIX M-4 3 WFC3/IR MULTIAC IR-UVIS- F160W none none none none 1 N/A CUM FIX M-4 4 WFC3/IR MULTIAC IR-UVIS- F160W none none none none 1 N/A CUM FIX 17683( 5) - 28-Oct-2025 19:10:27 - [ 6] Visit: 03 (M-4) Visit Requirements: ORIENT 280D TO 282 D; BETWEEN 01-APR-2025:00:00:00 AND 31-MAY-2025:00:00:00 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-4 WFC3/IR MULTIAC IR-UVIS-F F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG -5, 5 CUM IX (652.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 M-4 WFC3/IR MULTIAC IR-UVIS-F F110W SAMP-SEQ=SPARS50, NSAMP=14 1 DEF POS TARG -2.5, 2.5 CUM IX (652.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 M-4 WFC3/IR MULTIAC IR-UVIS-F F160W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF POS TARG 0, 0 CUM IX (602.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 M-4 WFC3/IR MULTIAC IR-UVIS-F F160W SAMP-SEQ=SPARS50, NSAMP=10 1 DEF POS TARG -7.5, 7.5 CUM IX (452.936 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-4 1 WFC3/IR MULTIAC IR-UVIS- F110W none none none none 1 N/A CUM FIX M-4 2 WFC3/IR MULTIAC IR-UVIS- F110W none none none none 1 N/A CUM FIX M-4 3 WFC3/IR MULTIAC IR-UVIS- F160W none none none none 1 N/A CUM FIX M-4 4 WFC3/IR MULTIAC IR-UVIS- F160W none none none none 1 N/A CUM FIX 17683( 5) - 28-Oct-2025 19:10:27 - [ 7] Visit: A1 (47Tuc Rolled) Visit Requirements: ORIENT 30D TO 65 D; BETWEEN 01-OCT-2025:00:00:00 AND 01-JAN-2026:00:00:00 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 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS25, NSAMP=13 1 DEF GS ACQ SCENARIO BASE1O3 CUM (302.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS10, NSAMP=10 1 DEF CUM (92.941 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS50, NSAMP=15 1 DEF CUM (702.939 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS25, NSAMP=15 1 DEF CUM (352.94 S) Comments: Designed to just saturate V=20 stars. ------------------------------------------------------------------------------------------------------------------------------------ 5 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS50, NSAMP=7 1 DEF CUM (302.935 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS10, NSAMP=10 1 DEF CUM (92.941 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS25, NSAMP=13 1 DEF POS TARG 4, 4 CUM (302.938 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 | ------------------------------------------------------------------------------------------------------------------------------------ DARK 1 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 47TUC 2 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM DARK 3 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 47TUC 4 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM DARK 5 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 17683( 5) - 28-Oct-2025 19:10:27 - [ 8] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 47TUC 6 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM 47TUC 7 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM 17683( 5) - 28-Oct-2025 19:10:27 - [ 9] Visit: B1 (47Tuc Rolled) Visit Requirements: ORIENT 30D TO 65 D; BETWEEN 01-NOV-2025:00:00:00 AND 31-JAN-2026:00:00:00 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 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS25, NSAMP=13 1 DEF GS ACQ SCENARIO BASE1O3 CUM (302.938 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS10, NSAMP=10 1 DEF CUM (92.941 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS50, NSAMP=15 1 DEF CUM (702.939 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS25, NSAMP=15 1 DEF CUM (352.94 S) Comments: Designed to just saturate V=20 stars. ------------------------------------------------------------------------------------------------------------------------------------ 5 DARK WFC3/IR MULTIAC IR BLANK SAMP-SEQ=SPARS50, NSAMP=7 1 DEF CUM (302.935 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS10, NSAMP=10 1 DEF CUM (92.941 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 47TUC WFC3/IR MULTIAC IR-FIX F160W SAMP-SEQ=SPARS25, NSAMP=13 1 DEF POS TARG 4, 4 CUM (302.938 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 | ------------------------------------------------------------------------------------------------------------------------------------ DARK 1 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 47TUC 2 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM DARK 3 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 47TUC 4 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM DARK 5 WFC3/IR MULTIAC IR BLANK none none none none 1 N/A CUM 17683( 5) - 28-Oct-2025 19:10:27 - [ 10] 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 | ------------------------------------------------------------------------------------------------------------------------------------ 47TUC 6 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM 47TUC 7 WFC3/IR MULTIAC IR-FIX F160W none none none none 1 N/A CUM 17683( 5) - 28-Oct-2025 19:10:27 - [ 11] Summary Form for Proposal 17683 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, IR-FIX, IR-UVIS-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=10, NSAMP=13, NSAMP=14, NSAMP=15, NSAMP=7, NSAMP=8, SAMP-SEQ=SPARS10, SAMP-SEQ=SPARS25, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-APR-2025:00:00:00 AND 31-MAY-2025:00:00:00, BETWEEN 01-JAN-2025:00:00:00 AND 15-MAR-2025:00:00:00, BETWEEN 01-NOV-2025:00:00:00 AND 31-JAN-2026:00:00:00, BETWEEN 01-OCT-2025:00:00:00 AND 01-JAN-2026:00:00:00, GS ACQ SCENARIO BASE1O3, ORIENT 280D TO 282 D, ORIENT 30D TO 65 D, ORIENT 310D TO 318 D, POS TARG -2.5, 2.5, POS TARG -5, 5, POS TARG -7.5, 7.5, POS TARG 0, 0, POS TARG 4, 4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements BLANK, F110W, F160W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 47TUC, DARK, M-4 ------------------------------------------------------------------------------------------------------------------------------------