17260( 3) - 23-Nov-2022 16:38:10 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17260 Version: 3 Check-in Time: 23-Nov-2022 16:38:10 STScI Edit Number: 1 Title WFC3 IR Time-Dependent Sensitivity: Clusters ------------------------------------------------------------------------------------ Type Cycle CAL/WFC3 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Varun Bajaj Space Telescope Science Institute Y CoI: Dr. Annalisa Calamida Space Telescope Science Institute N CoI: Ms. Jennifer Mack Space Telescope Science Institute N CoI: Dr. Debopam Som Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract The IR grism flux monitor shows a sensitivity loss of 0.12+/-0.01%/yr in G102 and 0.06+/-0.01%/yr in G141. Observations of flux standards in the IR filters, however, show no evidence of any loss over time, but the repeatability is limited by systematic errors of +/- 1%. Scanned observations of M35 from 2015-2020 show marginal losses of 0.024+/- 0.008%/yr in F140W, but these data show a large scatter which may be related to detector preconditioning. Cluster observations allow for the measurement of many more stars, and photometry of the core Omega-Cen used for distortion monitoring suggests losses of 0.23 +/- 0.03%/yr in F160W, but crowding may play an effect on the results. Recent observations of a less dense stellar field in M4 in F110W suggest losses of 0.13 +/- 0.02%/yr (first images only) and 0.20 +/- 0.03%/yr (all images), but these consist of only 4 visits. We propose continued monitoring of M4 at a ~6 month cadence. Two additional clusters are requested: the NGC104 field 6' from the core with F160W data from 2009-2013 and an Omega-Cen field 17' from the core with F110W & F160W images from 2016-2018, both of which mimic the observation strategy from the respective preceeding epochs, to eliminate systematics from differing observing modes. To continue the monitoring of the WFC3/IR sensitivity loss we observe the clusters M4 and 47Tuc using the same observation strategies in HST programs 16864 and 16512, continuing the monitors for a subset of the clusters observed in those programs. Spefically, we propose a single epoch of M4 (using both F110W and F160W) and two epochs of 47Tuc (using solely F160W). This allows continued measurement of the sensitivity losses from M4, which has multiple epochs of observation since 2020, and will help better constrain the sensitivity losses derived from the 47Tuc measurements, which otherwise only had only a single epoch of observation after 2014. We use the same filters, exposure times, and sample sequences as the corresponding previous observations to minimize any systematic effects caused by using different configurations, and employ the same dithering strategy to obtain consistent detector preconditioning. The 47Tuc observations will be separated by approximately 6 months (180 degree roll), to more evenly sample the temporal change. ------------------------------------------------------------------------------------ Observations Description ------------------------ In general, these observations copy the targets, sample sequences, NSamps, and orbit structure of previously obtained WFC3/IR observations in 16512, as this 17260( 3) - 23-Nov-2022 16:38:10 - [ 2] yields the fewest systematics when attempting to measure sensitivity losses over time. We propose a single M4 Visit to match Visit 01 of 16864, using the same filters, exposure times, sample sequences, dithers, and roll angle. This will help eliminate systematics when comparing the relative photometry. The visit consists 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 samples, due to the shorter orbital length (matching 16512). After each exposure POSTARGS of 2.5" will be applied, to mitigate self persistence. The first visit of WFC3/IR observations of 47 Tuc (visit 02) was configued to be similar to 16864 Visit 05, which itself was based on Visit 01 of 13563. As opposed to previous observations, the roll for the first epoch is constrained to be similar to 16964 Visit 05 (previous observations were unconstrained, leading to a mix of roll angles used). The structure of the visit itself is the same as 16864 (which itself differs be the next most recent epoch, from 13563, by changing the last dark to another F160W exposure). As performed in 16864 Visit 05, the last exposure is also dithered by approximately 40 pixels as this help mitigate the effect of self persistence. Visit 03 of this program repeates the observations of Visit02, but rolled at 180 degrees, and will take place approximately 6 months later, to better sample temporal changes in sensitivity. ------------------------------------------------------------------------------------ 17260( 3) - 23-Nov-2022 16:38:10 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M-4-V1 STELLAR CLUSTER, RA=16H23M41.5344S, J2000 V = 5.9 GLOBULAR CLUSTER DEC=-26D29'54.22" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 2 47TUC CALIBRATION, DETECTOR RA=00H22M27.8446S +/- 0.1", J2000 V = 22.0 LINEARITY TEST DEC=-72D04'4.75" +/- 0.1" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 17260( 3) - 23-Nov-2022 16:38:10 - [ 4] Visit: 01 (M-4) Visit Requirements: ORIENT 100.0D TO 102.0 D; BETWEEN 20-AUG-2023:00:00:00 AND 15-SEP-2023:00:00:00 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-V1 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-V1 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-V1 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-V1 WFC3/IR MULTIAC IR-UVIS-F F160W SAMP-SEQ=SPARS50, NSAMP=13 1 DEF POS TARG -7.5, 7.5 CUM IX (602.938 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 | ------------------------------------------------------------------------------------------------------------------------------------ M-4-V1 1 WFC3/IR MULTIAC IR-UVIS- F110W none none none none 1 N/A CUM FIX M-4-V1 2 WFC3/IR MULTIAC IR-UVIS- F110W none none none none 1 N/A CUM FIX M-4-V1 3 WFC3/IR MULTIAC IR-UVIS- F160W none none none none 1 N/A CUM FIX M-4-V1 4 WFC3/IR MULTIAC IR-UVIS- F160W none none none none 1 N/A CUM FIX 17260( 3) - 23-Nov-2022 16:38:10 - [ 5] Visit: 02 (47Tuc) Visit Requirements: ORIENT 120.D TO 135.0 D; BETWEEN 01-NOV-2022:00:00:00 AND 01-MAY-2023:00:00:00 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 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=15 1 DEF CUM (702.939 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 17260( 3) - 23-Nov-2022 16:38:10 - [ 6] 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 17260( 3) - 23-Nov-2022 16:38:10 - [ 7] Visit: 03 (47Tuc Rolled) Visit Requirements: ORIENT 179.9D TO 180D FROM 02; BETWEEN 01-AUG-2023:00:00:00 AND 01-NOV-2023:00:00:00 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 BASE1B3 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=15 1 DEF CUM (702.939 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 17260( 3) - 23-Nov-2022 16:38:10 - [ 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 17260( 3) - 23-Nov-2022 16:38:10 - [ 9] Summary Form for Proposal 17260 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, SAMP-SEQ=SPARS10, SAMP-SEQ=SPARS25, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-AUG-2023:00:00:00 AND 01-NOV-2023:00:00:00, BETWEEN 01-NOV-2022:00:00:00 AND 01-MAY-2023:00:00:00, BETWEEN 20-AUG-2023:00:00:00 AND 15-SEP-2023:00:00:00, GS ACQ SCENARIO BASE1B3, ORIENT 100.0D TO 102.0 D, ORIENT 120.D TO 135.0 D, ORIENT 179.9D TO 180D FROM 02, 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-V1 ------------------------------------------------------------------------------------------------------------------------------------