18250( 9) - 19-May-2026 21:30:39 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18250 Version: 9 Check-in Time: 19-May-2026 21:30:39 STScI Edit Number: 2 Title Mapping an M dwarf flare across time and color: simultaneous observations in the FUV and NIR ------------------------------------------------------------------------------------ Type Cycle GO/DD 33 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Hannah Diamond-Lowe Space Telescope Science Institute Y CoI: Natalie Allen The Johns Hopkins University N CoI: Dr. Nestor Espinoza Space Telescope Science Institute N CoI: Dr. Ward Howard University of Colorado at Boulder N CoI: Prof. Meredith MacGregor The Johns Hopkins University N CoI: Dra. Guadalupe Tovar Mendoza The Johns Hopkins University N ------------------------------------------------------------------------------------ Abstract There is a deepening body of literature demonstrating that M dwarfs flare at ultraviolet, optical, and infrared wavelengths throughout their lifetimes. At the same time, M dwarf flares inhibit our interpretation of planetary transmission spectra. No exoplanet system demonstrates this fact better than TRAPPIST-1, where transmission spectra of rocky planets are rife with stellar contamination. Rather than dwell on stellar contamination as a problem, here we propose use it to uncover the time-dependent and panchromatic nature of low-mass stellar flares. To do so we propose to align HST with already approved JWST multi-cycle Program 6456/9256 to capture a TRAPPIST-1 flare simultaneously in the far ultraviolet (FUV) and near infrared (NIR). Given the stringent time constraints of the accepted JWST program, this is a golden opportunity to unlock flare behavior over time and at two anchor points across the electromagnetic spectrum. The only opportunity to make these observations is rapidly approaching and we require the DD option to make this critical link between M dwarf flares in the FUV and NIR. We are requesting 6 HST/COS orbits to connect the FUV and NIR behavior of a TRAPPIST-1 flare. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will observe TRAPPIST-1 for 6 orbits using COS/G130M/1222A simultaneously with the Obs 13 of JWST GO 9256. ------------------------------------------------------------------------------------ 18250( 9) - 19-May-2026 21:30:39 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 TRAPPIST-1 STAR, BROWN DWARF RA=23H06M30.3652S +/- J2000 V = 18.798 0.00006155795", DEC=-05D02'36.70" +/- 0.000053622354" Reference Frame: ICRS Extended: NO Comments: Updated by PI from Gaia DR3. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016 0.062293722283178206 -0.4790375409528 0.0802123 ------------------------------------------------------------------------------------------------------------------------------------ 2 UCAC4-425-13 STAR, K V-IV RA=23H06M36.0092S +/- J2000 V = 14.97 2254 0.00003413762", DEC=-05D02'21.60" +/- 0.000029508391" Reference Frame: ICRS Extended: NO Comments: Updated by PI from Gaia DR3. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016 -2.25534748296741E-4 -0.005272569275000001 6.65E-4 ------------------------------------------------------------------------------------------------------------------------------------ 18250( 9) - 19-May-2026 21:30:39 - [ 3] Visit: 01 (COS/G130M) Visit Requirements: BETWEEN 06-JUN-2026:12:15:00 AND 06-JUN-2026:13:15:00 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 UCAC4-425-1 COS/NUV ACQ/IMA PSA MIRRORA 1 13 S (13 32254 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 1000 S G SEGMENT=BOTH, FP-POS=3 (1000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 720 S (720 G SEGMENT=BOTH, FP-POS=3 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 720 S (720 G SEGMENT=BOTH, FP-POS=3 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 842 S (842 G SEGMENT=BOTH, FP-POS=3 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 842 S (842 G SEGMENT=BOTH, FP-POS=3 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 UCAC4-425-1 COS/NUV ACQ/IMA PSA MIRRORA 1 13 S (13 32254 GE S) ------------------------------------------------------------------------------------------------------------------------------------ 8 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 870 S (870 G SEGMENT=BOTH, FP-POS=4 S) ------------------------------------------------------------------------------------------------------------------------------------ 9 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 870 S (870 G SEGMENT=BOTH, FP-POS=4 S) ------------------------------------------------------------------------------------------------------------------------------------ 10 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 1093 S G SEGMENT=BOTH, FP-POS=4 (1093 S) ------------------------------------------------------------------------------------------------------------------------------------ 11 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 1093 S G SEGMENT=BOTH, FP-POS=4 (1093 S) ------------------------------------------------------------------------------------------------------------------------------------ 12 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 1093 S G SEGMENT=BOTH, FP-POS=4 (1093 S) ------------------------------------------------------------------------------------------------------------------------------------ 13 TRAPPIST-1 COS/FUV TIME-TA PSA G130M 1291 BUFFER-TIME=5543, 1 1093 S G SEGMENT=BOTH, FP-POS=4 (1093 S) ------------------------------------------------------------------------------------------------------------------------------------ 18250( 9) - 19-May-2026 21:30:39 - [ 4] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ UCAC4-425-132254 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE TRAPPIST-1 2 COS/FUV TIME-TA PSA G130M 1291 none none none none 1 N/A G TRAPPIST-1 3 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G TRAPPIST-1 4 COS/FUV TIME-TA PSA G130M 1291 none none none none 2 N/A G TRAPPIST-1 5 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A G TRAPPIST-1 6 COS/FUV TIME-TA PSA G130M 1291 none none none none 3 N/A G UCAC4-425-132254 7 COS/NUV ACQ/IMA PSA MIRRORA none none none none 4 N/A GE TRAPPIST-1 8 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A G TRAPPIST-1 9 COS/FUV TIME-TA PSA G130M 1291 none none none none 4 N/A G TRAPPIST-1 10 COS/FUV TIME-TA PSA G130M 1291 none none none none 5 N/A G TRAPPIST-1 11 COS/FUV TIME-TA PSA G130M 1291 none none none none 5 N/A G TRAPPIST-1 12 COS/FUV TIME-TA PSA G130M 1291 none none none none 6 N/A G TRAPPIST-1 13 COS/FUV TIME-TA PSA G130M 1291 none none none none 6 N/A G 18250( 9) - 19-May-2026 21:30:39 - [ 5] Summary Form for Proposal 18250 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=5543, FP-POS=3, FP-POS=4, SEGMENT=BOTH ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 06-JUN-2026:12:15:00 AND 06-JUN-2026:13:15:00 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G130M, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names TRAPPIST-1, UCAC4-425-132254 ------------------------------------------------------------------------------------------------------------------------------------