18173( 2) - 11-Aug-2025 22:35:41 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18173 Version: 2 Check-in Time: 11-Aug-2025 22:35:41 STScI Edit Number: 0 Title STIS MAMA Fold Distribution ------------------------------------------------------------------------------------ Type Cycle CAL/STIS 33 ------------------------------------------------------------------------------------ Investigators Contact? PI: Sean Lockwood Space Telescope Science Institute Y CoI: Dr. Sergio B. Dieterich Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract The performance of MAMA microchannel plates can be monitored using a MAMA fold distribution procedure. The fold distribution provides a measurement of the distribution of charge cloud sizes incident upon the anode giving some measure of change in the pulse-height distribution of the MCP and, therefore, MCP gain. This proposal executes the same steps as the STIS MAMA Fold Distribution, Proposal 17648, as Cycle 32. ------------------------------------------------------------------------------------ Observations Description ------------------------ While globally illuminating the detector with a flat field, the valid event (VE) rate counter is monitored while various combinations of row and column folds are selected. The procedure is implemented using special commanding and is the same for the FUV and NUV MAMAs with the exception of the gratings/aperture/lamp combinations used for the flat fields. The procedure is described below and in STIS ISR 98-02R. The proposal nomenclature for the various anode fold configurations is: C2 = Column 2, R2 = Row 2, C3 = Column 3, R3 = Row 3, C4 = Column 4, R4 = Row 4, C5 = Column 5, R5 = Row 5, C6 = Column 6, and R6 = Row 6. The fold analysis is initiated by selecting the grating/aperture/lamp combination appropriate for the test. The following steps are then executed: Select the count rate monitor and average 5 samples; Repeat this for each of the count rate monitors X, Y, Z, W, VE, EV, OR; Disable all of the selectable folds (C2, C3, C4, C5, C6, R2, R3, R4, R5, R6); Collect 5 samples of VE with folds C2, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C2, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C2, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R4 enabled, other folds disabled; 18173( 2) - 11-Aug-2025 22:35:41 - [ 2] Collect 5 samples of VE with folds C4, R6 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R6 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R6 enabled, other folds disabled; Enable all selectable folds (C2, C3, C4, C5, C6, R2, R3, R4, R5, R6); Average 5 samples of EV and 5 samples of VE counts to measure any lamp drift; Turn off the lamp; Select the X count rate monitor and average 5 samples for the dark rate; Repeat this for each of the other count rate monitors (Y, Z, W, VE, EV, and OR); Restore the global monitor to its normal value. Analysis of the data is performed by creating a histogram binned by the sums of the fold numbers for columns and rows: C2R2 = 4 folds C2R3 + C3R2 = 5 folds C2R4 + C3R3 + C4R2 = 6 folds C3R4 + C4R3 = 7 folds C3R5 + C4R4 + C5R3 = 8 folds C4R5 + C5R4 = 9 folds C4R6 + C5R5 + C6R4 = 10 folds C5R6 + C6R5 = 11 folds C6R6 = 12 folds The sum of the 4 to 12 folds is equal to VE. The total number of events >= 4 folds is EV. The number of events greater than 12 folds is EV-VE. Generate a plot of 4 fold/EV, 5 fold/EV through 12 fold/EV, with (EV-VE)/EV on the abscissa and with the ordinate labeled 4 fold, 5 fold, through 12 fold. Results are sent to the Science Team and Steve Franka of Ball Aerospace . --------- Additional Comments ---------- Bright Object Protection Considerations. During the execution of the fold analysis some anode folds are disabled. Consequently, the OR counter does not provide a true representation of the OR count and so the Software Global Monitor (SGM) does not trigger until the enabled folds provide enough counts to the OR counter to trigger the SGM's threshold. To compensate, while the fold analysis is running the SGM threshold is reduced to 150, 000 counts (130, 000 counts are used due to ground system restrictions) in a 1.0 second interval, from its nominal value of 77, 000 counts in a 0.1 second interval. This test should only be run with the STIS extenal shutter closed. Special Commanding is used in this proposal. ------------------------------------------------------------------------------------ 18173( 2) - 11-Aug-2025 22:35:41 - [ 3] Visit: 01 (FUV Fold Test) Visit Requirements: BETWEEN 01-MAY-2026:00:00:00 AND 01-JUN-2026:00:00:00; PARALLEL On Hold Comments: Additional Comments: Schedule one FUV MAMA (M1) fold analysis visit per year. The FUV MAMA test is divided into three exposures with exposure 1 and 3 using S/C lines and special commanding 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 S/C DATA NONE 1 240.0 S SAA CONTOUR 25; SPEC COM (240 S) INSTR EOFOLDSET1; SAME ALIGNMENT 1-3 Comments: Set Software Global monitor (SGM), SGM Threshold = 15000, SGM Integration period = 0.1 secs. Configure mechanisms. Turn on HITM2 lamp at 10 mA. ------------------------------------------------------------------------------------------------------------------------------------ 2 DARK STIS/FUV ACCUM DEF DEF 1 300.0 S -MAMA (300 S) Comments: Take a "normal" DARK exposure with the HITM2 lamp on from S/C in exposure 01.001. Lamp remains on at the end of exposure. ------------------------------------------------------------------------------------------------------------------------------------ 18173( 2) - 11-Aug-2025 22:35:41 - [ 4] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 DARK S/C DATA NONE 1 2300.0 S SAA CONTOUR 25; SPEC COM (2300 S) INSTR EOFOLDTST1 Comments: FUV-MAMA (M1) flat filed details: Set Software Global monitor Threshold = 130000, SGM Integration period = 1.0 secs. Execute the following steps: Select the count rate monitor and collect 5 samples; Repeat this for each of the count rate monitors X, Y, Z, W, VE, EV, OR; Disable all of the selectable folds (C2, C3, C4, C5, C6, R2, R3, R4, R5, R6); Collect 5 samples of VE with folds C2, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C2, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C2, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R6 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R6 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R6 enabled, other folds disabled; Enable all selectable folds (C2, C3, C4, C5, C6, R2, R3, R4, R5, R6); Collect 5 samples of EV and 5 samples of VE counts to measure any lamp drift; Turn off the lamp; Select the X count rate monitor and collect 5 samples for the dark rate; Repeat this for each of the other count rate monitors (Y, Z, W, VE, EV, and OR); Restore the global monitor to its normal value. 18173( 2) - 11-Aug-2025 22:35:41 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 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 S/C DATA NONE none none none none 1 N/A DARK 2 STIS/FUV ACCUM DEF DEF none none none none 1 N/A -MAMA DARK 3 S/C DATA NONE none none none none 1 N/A 18173( 2) - 11-Aug-2025 22:35:41 - [ 6] Visit: 02 (NUV Fold Test) Visit Requirements: BETWEEN 01-MAY-2026:00:00:00 AND 01-JUN-2026:00:00:00; PARALLEL On Hold Comments: Additional Comments: Schedule one NUV MAMA (M2) fold analysis visit per year 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 S/C DATA NONE 1 240.0 S SAA CONTOUR 25; SPEC COM (240 S) INSTR EOFOLDSET2; SAME ALIGNMENT 1-3 Comments: Set Software Global monitor (SGM), SGM Threshold = 15000, SGM Integration period = 0.1 secs. Configure mechanisms Turn-on HITM1 lamp at 3.8 mA current. ------------------------------------------------------------------------------------------------------------------------------------ 2 DARK STIS/NUV ACCUM DEF DEF 1 120.0 S -MAMA (120 S) Comments: Take a "normal" DARK exposure with the HITM1 lamp on from S/C in exposure 02.001. Lamp remains on at the end of exposure. ------------------------------------------------------------------------------------------------------------------------------------ 18173( 2) - 11-Aug-2025 22:35:41 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 DARK S/C DATA NONE 1 2300.0 S SAA CONTOUR 25; SPEC COM (2300 S) INSTR EOFOLDTST2 Comments: NUV-MAMA (M2) flat field details: Set Software Global monitor SGM Threshold = 130000, SGM Integration period = 1.0 secs. Execute the following steps: Select the count rate monitor and collect 5 samples; Repeat this for each of the count rate monitors X, Y, Z, W, VE, EV, OR; Disable all of the selectable folds (C2, C3, C4, C5, C6, R2, R3, R4, R5, R6); Collect 5 samples of VE with folds C2, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C2, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C2, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R2 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C3, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R3 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C4, R6 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R4 enabled, other folds disabled; Collect 5 samples of VE with folds C5, R6 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R5 enabled, other folds disabled; Collect 5 samples of VE with folds C6, R6 enabled, other folds disabled; Enable all selectable folds (C2, C3, C4, C5, C6, R2, R3, R4, R5, R6); Collect 5 samples of EV and 5 samples of VE counts to measure any lamp drift; Turn off the lamp; Select the X count rate monitor and collect 5 samples for the dark rate; Repeat this for each of the other count rate monitors (Y, Z, W, VE, EV, and OR); Restore the global monitor to its normal value. 18173( 2) - 11-Aug-2025 22:35:41 - [ 8] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 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 S/C DATA NONE none none none none 1 N/A DARK 2 STIS/NUV ACCUM DEF DEF none none none none 1 N/A -MAMA DARK 3 S/C DATA NONE none none none none 1 N/A 18173( 2) - 11-Aug-2025 22:35:41 - [ 9] Summary Form for Proposal 18173 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures DEF, NONE ------------------------------------------------------------------------------------------------------------------------------------ Configurations S/C, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, DATA ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-MAY-2026:00:00:00 AND 01-JUN-2026:00:00:00, PARALLEL, SAA CONTOUR 25, SAME ALIGNMENT 1-3, SPEC COM INSTR EOFOLDSET1, SPEC COM INSTR EOFOLDSET2, SPEC COM INSTR EOFOLDTST1, SPEC COM INSTR EOFOLDTST2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements DEF ------------------------------------------------------------------------------------------------------------------------------------ Target Names DARK ------------------------------------------------------------------------------------------------------------------------------------