0 Assigned ID: 7467 ----- Attempting Submission 1 (Thu Apr 16 16:40:53 GMT 2026) ----- Could not connect to APT Status Server For the best data quality, it is generally required to use all four FP-POS positions at a given COS cenwave (or 2 positions for certain exception cases). See extended explanation in the diagnostic browser. For the best data quality, it is generally required to use all four FP-POS positions at a given COS cenwave (or 2 positions for certain exception cases). See extended explanation in the diagnostic browser. For the best data quality, it is generally required to use all four FP-POS positions at a given COS cenwave (or 2 positions for certain exception cases). See extended explanation in the diagnostic browser. 0 ----- Attempting Submission 1 (Mon Aug 17 16:51:43 GMT 2026) ----- While three of our visits have observations in only 2 FP-POS positions, these are additional exposures for targets that do have observations in all four FP-POS positions in other visits. In particular, each of these targets was awarded 5 orbits, which we have split into three visits (2+2+1). Given the faintness of the target, we split each orbit into only two explosures. As a result, we have 10 total exposures for each target of which there are either 2 or 3 in each FP-POS. Individual He II emitting stars - origin and contribution to galactic He II emission He II emission features are ubiquitously found in low-metallicity star-forming galaxy spectra, both locally and in the early Universe. However, none of the state-of-the-art spectral population synthesis codes can explain how it is produced. This suggests that we either poorly model the stellar ionizing sources, or have not incorporated all of them. We propose to observe the UV spectra of 4 newly discovered, individual He II emitters in the Large Magellanic Cloud in order to reveal their nature and assess their importance as contributors to the He II emission from galaxies. With optical spectra at hand, we identify three likely candidate types of stars-all which are products of binary interaction: binary stripped stars, rapidly accreting white dwarfs, and accreting black holes. The far-UV continuum slope and broad variety of spectral lines will allow us to distinguish. This program will obtain UV spectra for 4 targets in the LMC whose optical spectra show HeII emission. . The goal is to obtain UV spectra that can be modelled to determine the nature of the hot ionizing source in each system. Spectra will be obtained in the FUV with the G140L grism and a center wavelength of 800 AA, providing continuous wavelength coverage between ~900-1950 AA. We will obtain 3-5 orbits per targets (separated into multiple visits of between 1-3 orbits) and use all four FP positions for each target. The impacts of a reduced gyro operations on this program are primarily reduced schedualability due to the smaller field of regard, as well as possible impacts of roll angle constraints when avoiding placement of bright field objects in the second COS aperture. Slightly longer acquisition times have only a small effect on the S/N of our observations. All investigators on this proposal are experts in various aspects of massive star evolution and/or ionizing radiation from stellar populations. co-PIs Drout and Gotberg and Co-I Senchyna are all experienced HST/COS observers. Dr. Maria Drout is an expert in observational studies of evolved stellar populations in nearby galaxies, a wide range of supernova explosions, and other transients. Dr. Maria Drout is also an expert in observational studies of evolved stellar populations in nearby galaxies, a wide range of supernova explosions, and other transients. Dr. Ylva Gotberg works with theoretical studies using stellar evolution models and radiative transfer models to investigate products of mass stripping in close binary evolution, their predicted observational signatures, and their contribution to the radiation budget of stellar populations. Dr. Dimitrios Souropanis has substantial experience in both nebular spectral modeling of compact binaries that experience accretion, and binary population synthesis models. Dr. Peter Senchyna has ample observational experience and a scientific focus on massive low-metallicity stars and low mass, star-forming galaxies. Dr. Katie Auchettl is a multiwavelength observer with a focus on supernovae, supernova remnants, and stars. Alexander Laroche is a graduate student working with post-interaction binaries by measuring stellar properties and orbital parameters from spectroscopy. Dr. Bethany Ludwig has background in UV image reduction and detailed target selection of sources with UV excess. Stellar Populations and the Interstellar Medium Stellar Physics and Stellar Types 6 false true false false false false false SUPPORTED EXT-STAR BE COMPOSITE SPECTRAL TYPE EMISSION LINE NEBULA NO J2000 J2000 EXT-STAR BE COMPOSITE SPECTRAL TYPE EMISSION LINE NEBULA NO J2000 J2000 EXT-STAR DISK EMISSION LINE STAR NO J2000 J2000 EXT-STAR EMISSION LINE STAR WOLF RAYET NO J2000 J2000 COS/FUV Spectroscopic No No G140L 800 COS/FUV Spectroscopic No No G140L 800 COS/FUV Spectroscopic No No G140L 800 COS/FUV Spectroscopic No No G140L 800 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v01.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "01" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:25:50.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 122016 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2710 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "01" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 3 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v02.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "02" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:23:24.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 69792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "02" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 2 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v03.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "03" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:23:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 69792 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 2 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v04.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "04" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:25:17.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 34944 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 1 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v05.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "05" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:27:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 87168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "05" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "05" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 2 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v06.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "06" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:27:53.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 87168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "06" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "06" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 2 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v07.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "07" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:28:47.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 52320 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "07" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 1 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v08.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "08" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:30:02.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 87168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "08" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "08" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 2 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v09.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "09" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:30:32.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 87168 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "09" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 48 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) (Tic-Orbit :proposal-id 18367 :visit-id "09" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2711 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 2 0 /Users/mdrout/Documents/Proposals/HST/Cycle34/HeII_Ionizing/OP-cache/HeIIEmission_PhaseII-v10.xml The scheduling data was generated by CASM 34.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 18367 :visit-id "10" :proposal-version -1 :trans-version "20260618" :date "17-Aug-2026 11:30:58.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "31" :si-bright-earth-limb-angle 20.0 :data-volume 52320 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18367 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18367 :visit-id "10" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2712 :al-overhead-at-end 0 :internal-dur-at-end 357 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3092 :pcs-gap 0 ) true 1 0