17882( 5) - 07-Apr-2025 19:25:37 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17882 Version: 5 Check-in Time: 07-Apr-2025 19:25:37 STScI Edit Number: 0 Title Narrowband Imaging of NGC 6888 ------------------------------------------------------------------------------------ Type Cycle GO/DD 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Christopher Britt Space Telescope Science Institute Y CoI: Ryan Kunzer Space Telescope Science Institute N CoI: Max Mutchler Space Telescope Science Institute Y CoI: John Maple Space Telescope Science Institute N CoI: Varun Bajaj Space Telescope Science Institute Y CoI: Joseph DePasquale Space Telescope Science Institute Y CoI: Alyssa Pagan Space Telescope Science Institute Y CoI: Christine Pulliam Space Telescope Science Institute N CoI: Ray Villard Space Telescope Science Institute N CoI: Dr. Emma Marcucci Space Telescope Science Institute N ------------------------------------------------------------------------------------ Abstract We propose to take deep narrowband imaging of the Wolf-Rayet nebula NGC 6888. Deep H-alpha, [N II], and [OIII] images in F656N, F658N, and F502N will sample different density and temperature regions within the nebula. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain high signal-to-noise imaging of NGC 6888, the Crescent Nebula, in narrow-band filters F502N, F656N, and F658N as well as short bookend exposures in broadband filters F475W and F814W to provide color balance on the stars in the field. We propose a single WFC3 pointing which will cover a bright portion on the edge of the larger nebula. In the event of needing to retake a failed visit, we will attempt to match the Position Angle; in the event that this is not possible to schedule in Reduced Gyro Mode, we will make due with reduced dithers and use archival WFPC2 data to boost signal-to-noise if necessary. We will also employ a dither pattern which fills the chip gaps and enables cosmic ray rejection. The full nebula extends over a diameter of 20 arcmin, so we will focus on a particularly bright and turbulent edge of the nebula. Based on archival WFPC2 data, we estimate that high signal-to-noise images will require 2 orbits of F502N, 1 orbit of F656N, and 1 orbit of F658N, totalling 4 orbits. Most of the color composite will derive from the contrasting physical conditions promoting emission in [O III], [N II], and H-alpha. With exposure times calculated from existing archival WFPC2 observations, we can achieve the signal-to-noise desired with 4 orbits. Following a partial failure of Visit 01: After review, the Telescope Time Review Board (TTRB) approves your request and awards two orbits to repeat orbit #2 and #3 in Visit 01, which suffered failed guide-star reacquisition and loss of lock anomalies, leading to degraded data. The TTRB also approves your request to execute the repeats at the same ORIENT 17882( 5) - 07-Apr-2025 19:25:37 - [ 2] as the successful observations from Visit 01 or at 90 degrees offset from it. Visit 01 executed at an orientation of 294 deg in March 2025, and repeat visit 02 will execute at 201 deg in July 2025. Where get get two exposures of the same filter in visit 02, we include a standard y-shift gap dither and also a nonstandard x-shift which helps the repeat better match the footprint of the existing data from visit 01. ------------------------------------------------------------------------------------ 17882( 5) - 07-Apr-2025 19:25:37 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC-6888-EDG ISM, EMISSION LINE RA=20H12M32.9717S, J2000 V = 15 E NEBULA DEC=+38D27'11.03" Reference Frame: ICRS Extended: YES Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17882( 5) - 07-Apr-2025 19:25:37 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 10 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 89 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 5 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 89 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17882( 5) - 07-Apr-2025 19:25:37 - [ 5] Visit: 01 Visit Requirements: BEFORE 21-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 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F438W FLASH=20 1 60 S (120 PATTERN 1 1-3 GE S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F502N FLASH=20 2 1000 S GE S ER (4000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F814W FLASH=20 1 60 S (120 GE S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F656N FLASH=20 1 800 S PATTERN 2 4-5 GE S ER (2400 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F658N FLASH=20 1 700 S GE S ER (2100 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-6888-EDGE 1 WFC3/UVI ACCUM UVIS-CEN F438W 1 none none none 1 N/A S TER NGC-6888-EDGE 1 WFC3/UVI ACCUM UVIS-CEN F438W 2 none none none 2 N/A S TER NGC-6888-EDGE 2 WFC3/UVI ACCUM UVIS-CEN F502N 1 none 1 none 1 N/A S TER NGC-6888-EDGE 2 WFC3/UVI ACCUM UVIS-CEN F502N 1 none 2 none 1 N/A S TER NGC-6888-EDGE 2 WFC3/UVI ACCUM UVIS-CEN F502N 2 none 1 none 2 N/A S TER NGC-6888-EDGE 2 WFC3/UVI ACCUM UVIS-CEN F502N 2 none 2 none 2 N/A S TER NGC-6888-EDGE 3 WFC3/UVI ACCUM UVIS-CEN F814W 1 none none none 1 N/A S TER NGC-6888-EDGE 3 WFC3/UVI ACCUM UVIS-CEN F814W 2 none none none 2 N/A S TER NGC-6888-EDGE 4 WFC3/UVI ACCUM UVIS-CEN F656N 1 none none none 3 N/A S TER NGC-6888-EDGE 4 WFC3/UVI ACCUM UVIS-CEN F656N 2 none none none 3 N/A S TER 17882( 5) - 07-Apr-2025 19:25:37 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ NGC-6888-EDGE 4 WFC3/UVI ACCUM UVIS-CEN F656N 3 none none none 4 N/A S TER NGC-6888-EDGE 5 WFC3/UVI ACCUM UVIS-CEN F658N 1 none none none 3 N/A S TER NGC-6888-EDGE 5 WFC3/UVI ACCUM UVIS-CEN F658N 2 none none none 4 N/A S TER NGC-6888-EDGE 5 WFC3/UVI ACCUM UVIS-CEN F658N 3 none none none 4 N/A S TER 17882( 5) - 07-Apr-2025 19:25:37 - [ 7] Visit: 02 Visit Requirements: ORIENT 201D TO 201 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-6888-ED WFC3/UVI ACCUM UVIS-CENT F438W FLASH=20 1 60 S (60 GE S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F502N FLASH=20 1 1000 S GE S ER (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F502N FLASH=20 1 1000 S POS TARG -12, -2.4 GE S ER (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F814W FLASH=20 1 60 S (60 GE S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F656N FLASH=20 1 800 S (800 GE S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F658N FLASH=20 1 700 S (700 GE S ER S) ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC-6888-ED WFC3/UVI ACCUM UVIS-CENT F656N FLASH=20 1 800 S (800 POS TARG -12, -2.4 GE S ER 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-6888-EDGE 1 WFC3/UVI ACCUM UVIS-CEN F438W none none none none 1 N/A S TER NGC-6888-EDGE 2 WFC3/UVI ACCUM UVIS-CEN F502N none none none none 1 N/A S TER NGC-6888-EDGE 3 WFC3/UVI ACCUM UVIS-CEN F502N none none none none 1 N/A S TER NGC-6888-EDGE 4 WFC3/UVI ACCUM UVIS-CEN F814W none none none none 1 N/A S TER NGC-6888-EDGE 5 WFC3/UVI ACCUM UVIS-CEN F656N none none none none 2 N/A S TER NGC-6888-EDGE 6 WFC3/UVI ACCUM UVIS-CEN F658N none none none none 2 N/A S TER NGC-6888-EDGE 7 WFC3/UVI ACCUM UVIS-CEN F656N none none none none 2 N/A S TER 17882( 5) - 07-Apr-2025 19:25:37 - [ 8] Summary Form for Proposal 17882 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS-CENTER ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=20 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 21-MAR-2025:00:00:00, ORIENT 201D TO 201 D, PATTERN 1 1-3, PATTERN 2 4-5, POS TARG -12, -2.4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F438W, F502N, F656N, F658N, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC-6888-EDGE ------------------------------------------------------------------------------------------------------------------------------------