18357( 2) - 03-Aug-2026 17:32:05 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18357 Version: 2 Check-in Time: 03-Aug-2026 17:32:05 STScI Edit Number: 0 Title Domain expansion: Detecting the first extrasolar UV aurora with deep COS observations ------------------------------------------------------------------------------------ Type Cycle GO 34 ------------------------------------------------------------------------------------ Investigators Contact? PI: Ethen Sun University of Toronto Y CoI: Dr. Marta Bryan The Pennsylvania State University Y CoI: Dr. Yifan Zhou The University of Virginia N CoI: Dr. Laura Flagg The Pennsylvania State University Y CoI: Dr. Kurt David Retherford Southwest Research Institute N CoI: Dr. Joshua Kammer Southwest Research Institute N ------------------------------------------------------------------------------------ Abstract Aurora is the main thermodynamic driver in the upper atmospheres of our magnetized solar system planets, but its study here is complicated by the influence of an unpredictable solar wind. Free-floating brown dwarfs are powerful auroral engines suitable for testing aurora physics without this interference. However, existing radio and infrared observations cannot directly probe the results of the auroral precipitation process: for this the FUV emission produced by electrons impacting the hydrogen atmosphere is required. The FUV is the main emission mechanism and diagnostic tool for solar system aurora, and without this component the study of brown dwarf aurorae has reached a natural barrier. We propose deep observations of an extremely well studied auroral brown dwarf with HST/COS, in order to detect and study an extrasolar aurora in FUV for the first time. Because of the extensive atmospheric modelling for this target, we will be able to test multiple auroral luminosity predictions, compare it to Jupiter-based expectations, and measure the energetics and depth of the electron impact process. This discovery would have wide-ranging impacts in auroral, planetary, and brown dwarf physics at large, as well as permanently expanding the domain of UV astronomy. ------------------------------------------------------------------------------------ Observations Description ------------------------ We request 15 orbits of HST/COS at G140L/800 to observe the aurora of SIMP J0136+0933 in the far-UV. The emission bands of interest are the Werner band at 95-130 nm and the Lyman band at 155-165 nm. FUV aurora has never been observed outside the solar system and the target is not known to be a UV source. There is a suitable NUV source for blind offset acquisition located 30" south of the target. SCHEDULING: Program is divided into five 3-orbit visits that need to be executed within the span of about one week. There is a near-perfect 3:2 ratio between the target's rotation period and the HST's orbital period, so any 3 consecutive orbits ensures full phase coverage over 2 consecutive rotations. The constraint is so that the visits can be accurately phase folded: the target accumulates one radian of rotation phase error per week. ------------------------------------------------------------------------------------ 18357( 2) - 03-Aug-2026 17:32:05 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SIMP0136 STAR, BROWN DWARF, T RA=01H36M57.8999S +/- J2000 V = 25 For acquisition purposes only. 0.0003992", DEC=+09D33'47.05" G=19.41197 J=13.252 +/- 0.0002778" Reference Frame: ICRS Extended: NO Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 0.08372003007645354 -0.016156 0.1634478 ------------------------------------------------------------------------------------------------------------------------------------ 2 SIMP0136-OFF CALIBRATION, TARGET RA=01H36M58.3978S +/- J2000 V = 16.08 +/- 0.4 G=15.975 GALEX NUVmag SET ACQUISITION TEST 0.0000421", DEC=+09D33'19.94" 19.89(8) FUVmag N/A +/- 0.0000315" Reference Frame: ICRS Extended: NO Comments: ETC used Vmag and Pickles spectrum F8V based on Gaia Teff=6175.3 logg=4.2254 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2016.0 0.0014113827213860163 -0.009205 0.0002962 ------------------------------------------------------------------------------------------------------------------------------------ 18357( 2) - 03-Aug-2026 17:32:05 - [ 3] Visit: 01 Visit Requirements: GROUP 01, 02, 03, 04, 05 WITHIN 7D On Hold Comments: Additional Comments: 5 visits of 3 orbits each. Only requirement needed is group timing. This visit uses FP-POS 1, 2, 3 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 SIMP0136-OF COS/NUV ACQ/IMA PSA MIRRORA 1 12 S (12 FSET GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2224, SEGMENT=A, 1 1890 S G FP-POS=1, LIFETIME-POS=LP11 see below (2224 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=2, LIFETIME-POS=LP11 see below (2533 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=3, LIFETIME-POS=LP11 see below (2533 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 | ------------------------------------------------------------------------------------------------------------------------------------ SIMP0136-OFFSET 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE SIMP0136 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 2224.0 S G SIMP0136 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 2533.0 S G SIMP0136 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 2533.0 S G 18357( 2) - 03-Aug-2026 17:32:05 - [ 4] Visit: 02 Visit Requirements: GROUP 02, 01, 03, 04, 05 WITHIN 7D On Hold Comments: Additional Comments: 5 visits of 3 orbits each. Only requirement needed is group timing. This visit uses FP-POS 2, 3, 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 SIMP0136-OF COS/NUV ACQ/IMA PSA MIRRORA 1 12 S (12 FSET GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2224, SEGMENT=A, 1 1890 S G FP-POS=2, LIFETIME-POS=LP11 see below (2224 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=3, LIFETIME-POS=LP11 see below (2533 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=4, LIFETIME-POS=LP11 see below (2533 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 | ------------------------------------------------------------------------------------------------------------------------------------ SIMP0136-OFFSET 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE SIMP0136 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 2224.0 S G SIMP0136 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 2533.0 S G SIMP0136 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 2533.0 S G 18357( 2) - 03-Aug-2026 17:32:05 - [ 5] Visit: 03 Visit Requirements: GROUP 03, 01, 02, 04, 05 WITHIN 7D On Hold Comments: Additional Comments: 5 visits of 3 orbits each. Only requirement needed is group timing. This visit uses FP-POS 1, 2, 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 SIMP0136-OF COS/NUV ACQ/IMA PSA MIRRORA 1 12 S (12 FSET GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2224, SEGMENT=A, 1 1890 S G FP-POS=1, LIFETIME-POS=LP11 see below (2224 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=2, LIFETIME-POS=LP11 see below (2533 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=4, LIFETIME-POS=LP11 see below (2533 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 | ------------------------------------------------------------------------------------------------------------------------------------ SIMP0136-OFFSET 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE SIMP0136 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 2224.0 S G SIMP0136 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 2533.0 S G SIMP0136 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 2533.0 S G 18357( 2) - 03-Aug-2026 17:32:05 - [ 6] Visit: 04 Visit Requirements: GROUP 04, 01, 02, 03, 05 WITHIN 7D On Hold Comments: Additional Comments: 5 visits of 3 orbits each. Only requirement needed is group timing. This visit uses FP-POS 1, 3, 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 SIMP0136-OF COS/NUV ACQ/IMA PSA MIRRORA 1 12 S (12 FSET GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2224, SEGMENT=A, 1 1890 S G FP-POS=1, LIFETIME-POS=LP11 see below (2224 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=3, LIFETIME-POS=LP11 see below (2533 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=4, LIFETIME-POS=LP11 see below (2533 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 | ------------------------------------------------------------------------------------------------------------------------------------ SIMP0136-OFFSET 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE SIMP0136 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 2224.0 S G SIMP0136 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 2533.0 S G SIMP0136 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 2533.0 S G 18357( 2) - 03-Aug-2026 17:32:05 - [ 7] Visit: 05 Visit Requirements: GROUP 05, 01, 02, 03, 04 WITHIN 7D On Hold Comments: Additional Comments: 5 visits of 3 orbits each. Only requirement needed is group timing. This visit uses FP-POS 2, 3, 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 SIMP0136-OF COS/NUV ACQ/IMA PSA MIRRORA 1 12 S (12 FSET GE S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2224, SEGMENT=A, 1 1890 S G FP-POS=2, LIFETIME-POS=LP11 see below (2224 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=3, LIFETIME-POS=LP11 see below (2533 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SIMP0136 COS/FUV TIME-TA PSA G140L 800 BUFFER-TIME=2533, SEGMENT=A, 1 1890 S G FP-POS=4, LIFETIME-POS=LP11 see below (2533 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 | ------------------------------------------------------------------------------------------------------------------------------------ SIMP0136-OFFSET 1 COS/NUV ACQ/IMA PSA MIRRORA none none none none 1 N/A GE SIMP0136 2 COS/FUV TIME-TA PSA G140L 800 none none none none 1 2224.0 S G SIMP0136 3 COS/FUV TIME-TA PSA G140L 800 none none none none 2 2533.0 S G SIMP0136 4 COS/FUV TIME-TA PSA G140L 800 none none none none 3 2533.0 S G 18357( 2) - 03-Aug-2026 17:32:05 - [ 8] Summary Form for Proposal 18357 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PSA ------------------------------------------------------------------------------------------------------------------------------------ Configurations COS/FUV, COS/NUV ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/IMAGE, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=2224, BUFFER-TIME=2533, FP-POS=1, FP-POS=2, FP-POS=3, FP-POS=4, LIFETIME-POS=LP11, SEGMENT=A ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 01, 02, 03, 04, 05 WITHIN 7D, GROUP 02, 01, 03, 04, 05 WITHIN 7D, GROUP 03, 01, 02, 04, 05 WITHIN 7D, GROUP 04, 01, 02, 03, 05 WITHIN 7D, GROUP 05, 01, 02, 03, 04 WITHIN 7D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, MIRRORA ------------------------------------------------------------------------------------------------------------------------------------ Target Names SIMP0136, SIMP0136-OFFSET ------------------------------------------------------------------------------------------------------------------------------------