18386( 2) - 12-Aug-2026 19:35:26 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18386 Version: 2 Check-in Time: 12-Aug-2026 19:35:26 STScI Edit Number: 0 Title Probing the Existence of the Elusive Ultracompact White Dwarf Binaries in a Dense Globular Cluster ------------------------------------------------------------------------------------ Type Cycle GO 34 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Liliana Rivera Sandoval University of Texas Rio Grande Valley Y CoI: Manuel Pichardo Marcano National Autonomous University of Mexico N CoI: Prof. Thomas J. Maccarone Texas Tech University Y ------------------------------------------------------------------------------------ Abstract Globular clusters (GCs) are believed to be important factories of exotic binaries that harbor stellar remnants, which formation is enhanced due to dynamical interactions because of their high stellar densities. One of the populations expected to be abundant in GCs is the one of accreting double white dwarfs (or AM CVns). These are binaries with orbital periods between 5-70 min which lack H. However, not a single AM CVn has been confirmed yet in any GC, raising concerns about their existance in those very dense environments. This proposal aims to monitor in UV and narrow filter the low extinction and high stellar density globular cluster NGC 6752 to identify AM CVns via their transient behavior and photometric excesses. Using this innovative technique we will test dynamical formation and evolutionary models of these binaries in GCs. We will also compare their characteristics to the known population of AM CVns in the Galactic disk. Should the discovery of an upper limit on the identification rate be lower than anticipated, it would challenge the current understanding of GCs as efficient factories of compact binaries, particularly those containing white dwarfs. The study of white dwarf binaries in GCs will also have implications for the gravitational wave source detection in GCs with missions like LISA. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our goal is to identify blue transients in the cluster, especially those which are He-rich. The program is composed of 14 orbits divided in 9 visits. Visits 1 and 2 have 3 orbits each, visit 4 has 2 orbits and the remaining 6 have one orbit each. The primaries of the first 2 orbits of visits 1 and 2, and the first orbit of visit 3 are devoted to the filters F469N and F475W to detect helium. We took 2 images per filter per orbit to remove artifacts. We dedicated more time to the narrow filter F469N which has a very low transmission. We obtained around 1800s total per orbit in the filter F469N and 440s in the wider filter F475W. We think that despite having an exposure of 1000s in the narrow filter, its low transmission will prevent saturation. For the primaries in the UV (visits 1-9) we use the F225W and F275W filters on the UVIS channel of WFC3 in order to overcome the stellar crowding. We point at the center of the cluster. In order to remove cosmic rays and other artifacts 18386( 2) - 12-Aug-2026 19:35:26 - [ 2] we obtain 2 images per filter for a total of 4 per orbit. In orbits 1-9 each F225W observation has an exposure of 700s or less and the F275W observations have 600s or less, optimized to obtain the similar signal-to-noise. For the primaries, the strategy is the same for each of the 9 visits. We simultaneously obtain parallel observations with the WFC on the ACS. We are using 3 filters: F435W, F635W and F658N. Due to dumping and maneuver times to cover the chip gaps, we accomodate 4 parallel images per orbit. Our statrategy is to obtain 2 images in 2 different filters every orbit, alternating between the F435W and F658N filters between visits. This help us to remove cosmic rays and other artifacts each orbit, giving us reliable colors of the sources identified. For the first parallel visit we use the combination F625W and F435W, with longer exposures in F435W because it is the bluer filter. The total exposure times per orbit are around 320s for F625W and 630s for F435W, each divided in 2 observations. For the second parallel visit we use the combination F625W and F658N. In this case we give more weight to the narrow filter. Total exposure times are around 320s in F625W and 670s in F658N, divided in 2 observations each. Our third and fourth observations are similar to our first and second one, respectively. The rest repeat the pattern. We set up our dithers as POS-TARGS. We use similar values to the ones given by the WFC3-UVIS-MOSAIC-LINE strategy, which according to the documentation (section "C.2 WFC3 Patterns" of the WFC3 handbook) steps the gap on both detectors and it is used for full-frame WFC3-UVIS with ACS-WFC in parallel. The values used are X=1.446 arcsec, Y=2.926 arcsec and were set after the second primary observation in each visit. No timing restrictions for the first visit are placed. However, subsequent visits must be scheduled between 10-25 days from the previous one. We give a post flash of 17-20 e-/pix for each WFC3-UVIS images to account for the increasing CTE looses on the detector, as was recommended by the documentaion (ISR 2020-08: Strategies for Mitigation of CTE Losses in WFC3/UVIS) . ------------------------------------------------------------------------------------ 18386( 2) - 12-Aug-2026 19:35:26 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-6752 STELLAR CLUSTER, RA=19H10M52.1100S, J2000 V = 5.4 GLOBULAR CLUSTER DEC=-59D59'4.40" Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 18386( 2) - 12-Aug-2026 19:35:26 - [ 4] Visit: 01 Visit Requirements: 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=18 1 300 S (300 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=20 1 996 S (996 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F435W 1 310 S (310 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=17 1 800 S (800 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=17 1 140 S (140 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F435W 1 285 S (285 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=18 1 300 S (300 PAR 11-12 WITH 9-10 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=20 1 1000 S S ER (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 11 ANY ACS/WFC ACCUM WFCENTER F658N 1 330 S (330 S) ------------------------------------------------------------------------------------------------------------------------------------ 12 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=17 1 804 S (804 POS TARG 1.446, 2.926; S ER S) PAR 15-16 WITH 13-14 ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=17 1 140 S (140 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 18386( 2) - 12-Aug-2026 19:35:26 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 15 ANY ACS/WFC ACCUM WFCENTER F658N 1 285 S (285 S) ------------------------------------------------------------------------------------------------------------------------------------ 16 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 S) ------------------------------------------------------------------------------------------------------------------------------------ 17 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 19-20 WITH 17-18 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 18 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 697 S (697 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 19 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 20 ANY ACS/WFC ACCUM WFCENTER F435W 1 300 S (300 S) ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 23-24 WITH 21-22 ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 477 S (477 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 23 ANY ACS/WFC ACCUM WFCENTER F435W 1 320 S (320 S) ------------------------------------------------------------------------------------------------------------------------------------ 24 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A NGC-6752 9 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 2 N/A S TER NGC-6752 10 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 2 N/A S TER ANY 11 ACS/WFC ACCUM WFCENTER F658N none none none none 2 N/A ANY 12 ACS/WFC ACCUM WFCENTER F625W none none none none 2 N/A NGC-6752 13 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 2 N/A S TER NGC-6752 14 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 2 N/A S TER ANY 15 ACS/WFC ACCUM WFCENTER F658N none none none none 2 N/A ANY 16 ACS/WFC ACCUM WFCENTER F625W none none none none 2 N/A NGC-6752 17 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 3 N/A S TER NGC-6752 18 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 3 N/A S TER ANY 19 ACS/WFC ACCUM WFCENTER F625W none none none none 3 N/A ANY 20 ACS/WFC ACCUM WFCENTER F435W none none none none 3 N/A NGC-6752 21 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 3 N/A S TER NGC-6752 22 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 3 N/A S TER ANY 23 ACS/WFC ACCUM WFCENTER F435W none none none none 3 N/A ANY 24 ACS/WFC ACCUM WFCENTER F625W none none none none 3 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 7] Visit: 02 Visit Requirements: AFTER 01 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=18 1 300 S (300 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=20 1 996 S (996 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F435W 1 310 S (310 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=17 1 800 S (800 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=17 1 140 S (140 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F435W 1 285 S (285 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=18 1 300 S (300 PAR 11-12 WITH 9-10 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=20 1 1000 S S ER (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 11 ANY ACS/WFC ACCUM WFCENTER F658N 1 330 S (330 S) ------------------------------------------------------------------------------------------------------------------------------------ 12 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=17 1 804 S (804 POS TARG 1.446, 2.926; S ER S) PAR 15-16 WITH 13-14 ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=17 1 140 S (140 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 18386( 2) - 12-Aug-2026 19:35:26 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 15 ANY ACS/WFC ACCUM WFCENTER F658N 1 285 S (285 S) ------------------------------------------------------------------------------------------------------------------------------------ 16 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 S) ------------------------------------------------------------------------------------------------------------------------------------ 17 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 19-20 WITH 17-18 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 18 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 684 S (684 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 19 ANY ACS/WFC ACCUM WFCENTER F625W 1 220 S (220 S) ------------------------------------------------------------------------------------------------------------------------------------ 20 ANY ACS/WFC ACCUM WFCENTER F658N 1 320 S (320 S) ------------------------------------------------------------------------------------------------------------------------------------ 21 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 23-24 WITH 21-22 ------------------------------------------------------------------------------------------------------------------------------------ 22 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 490 S (490 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 23 ANY ACS/WFC ACCUM WFCENTER F658N 1 354 S (354 S) ------------------------------------------------------------------------------------------------------------------------------------ 24 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 9] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A NGC-6752 9 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 2 N/A S TER NGC-6752 10 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 2 N/A S TER ANY 11 ACS/WFC ACCUM WFCENTER F658N none none none none 2 N/A ANY 12 ACS/WFC ACCUM WFCENTER F625W none none none none 2 N/A NGC-6752 13 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 2 N/A S TER NGC-6752 14 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 2 N/A S TER ANY 15 ACS/WFC ACCUM WFCENTER F658N none none none none 2 N/A ANY 16 ACS/WFC ACCUM WFCENTER F625W none none none none 2 N/A NGC-6752 17 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 3 N/A S TER NGC-6752 18 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 3 N/A S TER ANY 19 ACS/WFC ACCUM WFCENTER F625W none none none none 3 N/A ANY 20 ACS/WFC ACCUM WFCENTER F658N none none none none 3 N/A NGC-6752 21 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 3 N/A S TER NGC-6752 22 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 3 N/A S TER ANY 23 ACS/WFC ACCUM WFCENTER F658N none none none none 3 N/A ANY 24 ACS/WFC ACCUM WFCENTER F625W none none none none 3 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 10] Visit: 03 Visit Requirements: AFTER 02 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=18 1 300 S (300 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=20 1 996 S (996 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F658N 1 330 S (330 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F469N FLASH=17 1 800 S (800 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F475W FLASH=17 1 140 S (140 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F658N 1 285 S (285 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 11-12 WITH 9-10 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 684 S (684 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 11 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 12 ANY ACS/WFC ACCUM WFCENTER F435W 1 300 S (300 S) ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 15-16 WITH 13-14 ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 490 S (490 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 18386( 2) - 12-Aug-2026 19:35:26 - [ 11] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 15 ANY ACS/WFC ACCUM WFCENTER F435W 1 333 S (333 S) ------------------------------------------------------------------------------------------------------------------------------------ 16 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F469N none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F475W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A NGC-6752 9 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 2 N/A S TER NGC-6752 10 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 2 N/A S TER ANY 11 ACS/WFC ACCUM WFCENTER F625W none none none none 2 N/A ANY 12 ACS/WFC ACCUM WFCENTER F435W none none none none 2 N/A NGC-6752 13 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 2 N/A S TER NGC-6752 14 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 2 N/A S TER ANY 15 ACS/WFC ACCUM WFCENTER F435W none none none none 2 N/A ANY 16 ACS/WFC ACCUM WFCENTER F625W none none none none 2 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 12] Visit: 04 Visit Requirements: AFTER 03 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F625W 1 220 S (220 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F658N 1 320 S (320 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 489 S (489 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F658N 1 354 S (354 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 13] Visit: 05 Visit Requirements: AFTER 04 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F435W 1 300 S (300 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 489 S (489 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F435W 1 332 S (332 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 14] Visit: 06 Visit Requirements: AFTER 05 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F625W 1 220 S (220 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F658N 1 320 S (320 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 489 S (489 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F658N 1 354 S (354 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 15] Visit: 07 Visit Requirements: AFTER 06 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F435W 1 300 S (300 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 489 S (489 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F435W 1 332 S (332 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 16] Visit: 08 Visit Requirements: AFTER 07 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F625W 1 220 S (220 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F658N 1 320 S (320 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 489 S (489 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F658N 1 354 S (354 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F658N none none none none 1 N/A ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 17] Visit: 09 Visit Requirements: AFTER 08 BY 10 D TO 25 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 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 600 S (600 PAR 3-4 WITH 1-2 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 700 S (700 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ANY ACS/WFC ACCUM WFCENTER F625W 1 200 S (200 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFCENTER F435W 1 300 S (300 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F225W FLASH=17 1 450 S (450 POS TARG 1.446, 2.926; S ER S) PAR 7-8 WITH 5-6 ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6752 WFC3/UVI ACCUM UVIS-CENT F275W FLASH=18 1 489 S (489 POS TARG 1.446, 2.926 S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ANY ACS/WFC ACCUM WFCENTER F435W 1 332 S (332 S) ------------------------------------------------------------------------------------------------------------------------------------ 8 ANY ACS/WFC ACCUM WFCENTER F625W 1 100 S (100 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6752 1 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER NGC-6752 2 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER ANY 3 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A ANY 4 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A NGC-6752 5 WFC3/UVI ACCUM UVIS-CEN F225W none none none none 1 N/A S TER NGC-6752 6 WFC3/UVI ACCUM UVIS-CEN F275W none none none none 1 N/A S TER ANY 7 ACS/WFC ACCUM WFCENTER F435W none none none none 1 N/A ANY 8 ACS/WFC ACCUM WFCENTER F625W none none none none 1 N/A 18386( 2) - 12-Aug-2026 19:35:26 - [ 18] Summary Form for Proposal 18386 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS-CENTER, WFCENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=17, FLASH=18, FLASH=20 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 10 D TO 25 D, AFTER 02 BY 10 D TO 25 D, AFTER 03 BY 10 D TO 25 D, AFTER 04 BY 10 D TO 25 D, AFTER 05 BY 10 D TO 25 D, AFTER 06 BY 10 D TO 25 D, AFTER 07 BY 10 D TO 25 D, AFTER 08 BY 10 D TO 25 D, PAR 11-12 WITH 9-10, PAR 15-16 WITH 13-14, PAR 19-20 WITH 17-18, PAR 23-24 WITH 21-22, PAR 3-4 WITH 1-2, PAR 7-8 WITH 5-6, POS TARG 1.446, 2.926 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F225W, F275W, F435W, F469N, F475W, F625W, F658N ------------------------------------------------------------------------------------------------------------------------------------ Target Names ANY, NGC-6752 ------------------------------------------------------------------------------------------------------------------------------------