17909( 5) - 17-Dec-2025 21:18:33 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17909 Version: 5 Check-in Time: 17-Dec-2025 21:18:33 STScI Edit Number: 1 Title Rest-Frame [O III] Imaging of Post-Starburst TDE Hosts with Extended Emission Line Regions ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Jason Hinkle University of Illinois at Urbana - Y Champaign CoI: Prof. Benjamin John Shappee University of Hawaii N ------------------------------------------------------------------------------------ Abstract Post-starburst galaxies, with little current star formation but evidence of a recent large burst, are promising probes of the transition between star-forming and quiescent galaxies. The cause of the rapid quenching of star formation is debated, with gas-rich mergers, stellar feedback, and active galactic nucleus (AGN) feedback all plausible explanations. Recent studies have discovered extended [O III] emission line regions (EELRs) in several post-starburst galaxies, inconsistent with current AGN activity but compatible with AGN activity over the past several thousand years. Interestingly, many post-starburst galaxies with EELRs have also been hosts to recent tidal disruption events (TDEs), a transient class for which post-starburst galaxies are highly overrepresented as host galaxies. Here we propose to obtain an epoch of narrow-band rest-frame [O III] (FR505N) and medium-band continuum (FR647M) imaging of three post-starburst TDE hosts with observed EELRs to more finely map their spatial distribution. These observations require the use of the ramp filters on ACS/WFC. The high spatial resolution [O III] images will address important questions about the interplay between AGN activity and the nature of post-starburst galaxies. We will (1) test the possibility that TDEs power the EELRs through a search for shells of emission, (2) constrain the AGN active lifetime from the most distant EELR, and (3) provide insight into the connection between diverse forms of nuclear SMBH activity like AGNs, TDEs, and quasi-periodic eruptions. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program aims to observe extended emission line regions (EELRs) in three nearby TDE host galaxies. The three host galaxies are those of ASASSN-14li, iPTF16fl, and ASASSN-19dj. Each has exisiting IFU data showing the prescence and distribution of known EELRs. These HST ACS/WFC data will dramatically increase the spatial resolution with which we can measure the difuse [O III] flux in addition to modestly expanding the field of view allowing us to observe more distant EELRs. We will use the FR505N ramp filter of ACS/WFC to obtain rest-frame [O III] imaging for these host galaixes. For the redshifts of the hosts, ASASSN-14li (z = 0.0206), iPTF16fnl (z = 0.016328), and ASASSN-19dj (z = 0.022346), the strong [O III] line at lambda = 5007 is at an observed wavelength of 5110 A, 5089 A, and 5119 A respectively, all accessible to FR505N. Given the low equivalent widths of some known EELRs, we additionally will use the FR647M ramp filter to 17909( 5) - 17-Dec-2025 21:18:33 - [ 2] measure the spatial distribution of the stellar continuum emission, which can then be subtracted to yield an [O III]-only image. The known EELR positions for ASASSN-14li and ASASSN-19dj allow for any orientation to capture the EELRs within the monochromatic extent of the ramp filters. However, the known positions of EELRs in the host galaxy of iPTF16fnl means that some orientation angles will exclude known regions. Using APT and the WFC1-MRAMPQ aperture for the FR505N filter, we find that orient ranges of 75 - 130 degrees and 255 - 310 degrees will include the known EELRs within the monochromatic extent of FR505N. Other orientations will miss more distant EELRs and are therefore not feasible. We have maximized the acceptable orient range to increase the schedulability of the observations. ------------------------------------------------------------------------------------ 17909( 5) - 17-Dec-2025 21:18:33 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ASASSN-14LI- GALAXY, ELLIPTICAL, RA=12H48M15.2300S, J2000 V = 15.45 +/- 0.05 Host-galaxy V-band HOST SHELL DEC=+17D46'26.44" magnitude estimated from ASAS-SN light curve. Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 2 IPTF16FNL-HO GALAXY, DISK, SHELL RA=00H29M57.0420S, J2000 V = 15.33 +/- 0.05 Host-galaxy V-band ST DEC=+32D53'37.51" magnitude estimated from ASAS-SN light curve. Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 3 ASASSN-19DJ- GALAXY, ELLIPTICAL, RA=08H13M16.9450S, J2000 V = 14.89 +/- 0.05 Host-galaxy V-band HOST SHELL DEC=+22D38'54.03" magnitude estimated from ASAS-SN light curve. Reference Frame: ICRS Extended: YES ------------------------------------------------------------------------------------------------------------------------------------ 17909( 5) - 17-Dec-2025 21:18:33 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.125 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 135 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.125 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 135 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17909( 5) - 17-Dec-2025 21:18:33 - [ 5] Visit: 01 (ASASSN-14li_imaging) 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 ASASSN-14LI ACS/WFC ACCUM WFC1-MRAM FR505N 5110 FLASH=20 1 1115 S PATTERN 2 1 -HOST PQ (3345 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ASASSN-14LI ACS/WFC ACCUM WFC1-MRAM FR505N 5110 FLASH=20 1 1156 S PATTERN 2 2 -HOST PQ (3468 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 ASASSN-14LI ACS/WFC ACCUM WFC1-MRAM FR505N 5110 FLASH=20 1 826 S PATTERN 3 3 -HOST PQ (1652 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 ASASSN-14LI ACS/WFC ACCUM WFC1-IRAM FR647M 5750 FLASH=20 1 37 S (111 PATTERN 2 4 -HOST PQ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ASASSN-14LI-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5110 1 none none none 1 N/A MPQ ASASSN-14LI-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5110 2 none none none 1 N/A MPQ ASASSN-14LI-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5110 3 none none none 2 N/A MPQ ASASSN-14LI-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5110 1 none none none 2 N/A MPQ ASASSN-14LI-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5110 2 none none none 3 N/A MPQ ASASSN-14LI-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5110 3 none none none 3 N/A MPQ ASASSN-14LI-HOST 3 ACS/WFC ACCUM WFC1-MRA FR505N 5110 1 none none none 4 N/A MPQ ASASSN-14LI-HOST 3 ACS/WFC ACCUM WFC1-MRA FR505N 5110 2 none none none 4 N/A MPQ ASASSN-14LI-HOST 4 ACS/WFC ACCUM WFC1-IRA FR647M 5750 1 none none none 4 N/A MPQ ASASSN-14LI-HOST 4 ACS/WFC ACCUM WFC1-IRA FR647M 5750 2 none none none 4 N/A MPQ ASASSN-14LI-HOST 4 ACS/WFC ACCUM WFC1-IRA FR647M 5750 3 none none none 4 N/A MPQ 17909( 5) - 17-Dec-2025 21:18:33 - [ 6] Visit: 02 (iPTF16fnl_imaging) Visit Requirements: ORIENT 75D TO 130 D; ORIENT 255D TO 310 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 IPTF16FNL-H ACS/WFC ACCUM WFC1-MRAM FR505N 5089 FLASH=20 1 699 S PATTERN 2 1 OST PQ (2097 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 IPTF16FNL-H ACS/WFC ACCUM WFC1-MRAM FR505N 5089 FLASH=20 1 713 S PATTERN 2 2 OST PQ (2139 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 IPTF16FNL-H ACS/WFC ACCUM WFC1-MRAM FR505N 5089 FLASH=20 1 477 S PATTERN 2 3 OST PQ (1431 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 IPTF16FNL-H ACS/WFC ACCUM WFC1-IRAM FR647M 5750 FLASH=20 1 59 S (177 PATTERN 2 4 OST PQ 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 | ------------------------------------------------------------------------------------------------------------------------------------ IPTF16FNL-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5089 1 none none none 1 N/A MPQ IPTF16FNL-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5089 2 none none none 1 N/A MPQ IPTF16FNL-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5089 3 none none none 1 N/A MPQ IPTF16FNL-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5089 1 none none none 2 N/A MPQ IPTF16FNL-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5089 2 none none none 2 N/A MPQ IPTF16FNL-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5089 3 none none none 2 N/A MPQ IPTF16FNL-HOST 3 ACS/WFC ACCUM WFC1-MRA FR505N 5089 1 none none none 3 N/A MPQ IPTF16FNL-HOST 3 ACS/WFC ACCUM WFC1-MRA FR505N 5089 2 none none none 3 N/A MPQ IPTF16FNL-HOST 3 ACS/WFC ACCUM WFC1-MRA FR505N 5089 3 none none none 3 N/A MPQ IPTF16FNL-HOST 4 ACS/WFC ACCUM WFC1-IRA FR647M 5750 1 none none none 3 N/A MPQ IPTF16FNL-HOST 4 ACS/WFC ACCUM WFC1-IRA FR647M 5750 2 none none none 3 N/A MPQ IPTF16FNL-HOST 4 ACS/WFC ACCUM WFC1-IRA FR647M 5750 3 none none none 3 N/A MPQ 17909( 5) - 17-Dec-2025 21:18:33 - [ 7] Visit: 03 (ASASSN-19dj_imaging) 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 ASASSN-19DJ ACS/WFC ACCUM WFC1-MRAM FR505N 5119 FLASH=20 1 437 S PATTERN 2 1 -HOST PQ (1311 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ASASSN-19DJ ACS/WFC ACCUM WFC1-IRAM FR647M 5750 FLASH=20 1 70 S (210 PATTERN 2 2 -HOST PQ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ASASSN-19DJ-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5119 1 none none none 1 N/A MPQ ASASSN-19DJ-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5119 2 none none none 1 N/A MPQ ASASSN-19DJ-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5119 3 none none none 1 N/A MPQ ASASSN-19DJ-HOST 2 ACS/WFC ACCUM WFC1-IRA FR647M 5750 1 none none none 1 N/A MPQ ASASSN-19DJ-HOST 2 ACS/WFC ACCUM WFC1-IRA FR647M 5750 2 none none none 1 N/A MPQ ASASSN-19DJ-HOST 2 ACS/WFC ACCUM WFC1-IRA FR647M 5750 3 none none none 1 N/A MPQ 17909( 5) - 17-Dec-2025 21:18:33 - [ 8] Visit: 2A (iPTF16fnl_imaging) Visit Requirements: ORIENT 75D TO 130 D; ORIENT 255D TO 310 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 IPTF16FNL-H ACS/WFC ACCUM WFC1-MRAM FR505N 5089 FLASH=20 1 713 S PATTERN 2 1 OST PQ (2139 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 IPTF16FNL-H ACS/WFC ACCUM WFC1-MRAM FR505N 5089 FLASH=20 1 477 S PATTERN 2 2 OST PQ (1431 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 IPTF16FNL-H ACS/WFC ACCUM WFC1-IRAM FR647M 5750 FLASH=20 1 59 S (177 PATTERN 2 3 OST PQ 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 | ------------------------------------------------------------------------------------------------------------------------------------ IPTF16FNL-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5089 1 none none none 1 N/A MPQ IPTF16FNL-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5089 2 none none none 1 N/A MPQ IPTF16FNL-HOST 1 ACS/WFC ACCUM WFC1-MRA FR505N 5089 3 none none none 1 N/A MPQ IPTF16FNL-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5089 1 none none none 2 N/A MPQ IPTF16FNL-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5089 2 none none none 2 N/A MPQ IPTF16FNL-HOST 2 ACS/WFC ACCUM WFC1-MRA FR505N 5089 3 none none none 2 N/A MPQ IPTF16FNL-HOST 3 ACS/WFC ACCUM WFC1-IRA FR647M 5750 1 none none none 2 N/A MPQ IPTF16FNL-HOST 3 ACS/WFC ACCUM WFC1-IRA FR647M 5750 2 none none none 2 N/A MPQ IPTF16FNL-HOST 3 ACS/WFC ACCUM WFC1-IRA FR647M 5750 3 none none none 2 N/A MPQ 17909( 5) - 17-Dec-2025 21:18:33 - [ 9] Summary Form for Proposal 17909 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC1-IRAMPQ, WFC1-MRAMPQ ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=20 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 255D TO 310 D, ORIENT 75D TO 130 D, PATTERN 2 1, PATTERN 2 2, PATTERN 2 3, PATTERN 2 4, PATTERN 3 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements FR505N, FR647M ------------------------------------------------------------------------------------------------------------------------------------ Target Names ASASSN-14LI-HOST, ASASSN-19DJ-HOST, IPTF16FNL-HOST ------------------------------------------------------------------------------------------------------------------------------------