0 Assigned ID: 4609 ----- Attempting Submission 1 (Wed May 24 20:34:48 GMT 2023) ----- 0 ----- Attempting Submission 1 (Thu Sep 14 19:27:29 GMT 2023) ----- Heavy metals escaping from a hot Neptune A large fraction of known exoplanets orbit their host stars at very short periods. Due to such close proximity to the parent star, their atmospheres are exposed to high levels of stellar radiation and stellar wind, as well as strong tidal interactions, which can lead to atmospheric escape operating in a regime much more efficient than in the Solar System planets. Efficient atmospheric mass loss has the power to radically transform planets by changing their atmospheric structure or by removing the atmosphere altogether. Even though the first evidence of ongoing atmospheric escape in exoplanets was acquired for close-in gas giants, exoplanet demographics suggest that this process likely plays a much greater evolutionary role in planets the size of Neptune and smaller. It is believed to be responsible for shaping the so-called 'hot Neptune desert', the observed paucity of intermediate-sized planets at close orbital separations. LTT 9779b is a rare example of a planet residing well within this desert, in the part of the parameter space where atmospheric escape driven by stellar high-energy radiation can be further assisted by Roche lobe overflow, resulting in extremely high mass-loss rates. The goal of our proposal is to observe the ongoing atmospheric escape for this ultra-hot Neptune through transmission spectroscopy at NUV wavelengths with STIS. The NUV wavelength range gives us the best opportunity to observe the upper atmosphere in multiple lines of different species, which is necessary in order to break modeling degeneracies and constrain the atmospheric mass-loss rate. We will observe the transiting exoplanet system LTT 9779 with five visits of three orbits each. Each visit will be centered around a transit of the planet LTT 9779b, which has an orbital period of 0.79 days, allowing for frequent observing opportunities. Each of the five visits must be a non-interrupted sequence in order to cover a pre-transit baseline with the first orbit, the transit itself in the second orbit, and the post-transit baseline with the third orbit. Target acquisition will be performed with the recommended F28X50LP filter, and 0.2s exposure times. This is below the saturation time of 0.33s. The rest of the observing time will be dedicated to spectroscopy with the E230M echelle. The buffer time given by the exposure time calculator is 617 s. We have therefore used the recommended 4/5 value of 493 s. Antonija Oklopcic is an expert in the theoretical modelling of escaping exoplanet atmospheres. Dion Linssen is a graduate student working with AO on modeling atmospheric escape. Jessica Spake is an observer with a focus on escaping exoplanet atmospheres. She has led four successful HST programs. Heather Knutson is an expert in the analysis of exoplanet atmosphere observations. She has led and Co-Id over 10 HST programs. Exoplanets and Exoplanet Formation 6 false true false false false false SUPPORTED EXT-STAR EXTRA-SOLAR PLANETARY SYSTEM G V-IV NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 STIS/NUV-MAMA Spectroscopic No No E230M 2707 Phase windows are not calculated when the gap between schedulable intervals is less than 1 days, assuming no scheduling restrictions for constraint Phase 0.898/0.908. The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. It is essential that the three orbits be scheduled in a coninuous block. 1702974855000 69.9098172987195 (Tic-Visit :proposal-id 17460 :visit-id "01" :proposal-version -1 :trans-version "20230626" :date "14-Sep-2023 12:21:46.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1165888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17460 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17460 :visit-id "01" :orbit-number 1 :pcs-time 443 :si-vis-utilization 2463 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "01" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "01" :orbit-number 3 :pcs-time 392 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 578 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) false 3 0 Phase windows are not calculated when the gap between schedulable intervals is less than 1 days, assuming no scheduling restrictions for constraint Phase 0.898/0.908. The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. 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The scheduling data was generated by CASM 32.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/williamj/hst/work/cycle31/OP-cache/17460-v03.xml It is essential that the three orbits be scheduled in a coninuous block. 1719467004000 255.28521396043232 (Tic-Visit :proposal-id 17460 :visit-id "03" :proposal-version -1 :trans-version "20240604" :date "11-Jun-2024 13:33:44.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1165888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17460 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17460 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2463 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "03" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 578 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) false 3 0 Phase windows are not calculated when the gap between schedulable intervals is less than 1 days, assuming no scheduling restrictions for constraint Phase 0.898/0.908. The scheduling data was generated by CASM 32.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/williamj/hst/work/cycle31/OP-cache/17460-v04.xml It is essential that the three orbits be scheduled in a coninuous block. 1721588551000 267.9858601155029 (Tic-Visit :proposal-id 17460 :visit-id "04" :proposal-version -1 :trans-version "20240604" :date "11-Jun-2024 13:33:45.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1165888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17460 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17460 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2463 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "04" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "04" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 578 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) false 3 0 Phase windows are not calculated when the gap between schedulable intervals is less than 1 days, assuming no scheduling restrictions for constraint Phase 0.898/0.908. The scheduling data was generated by CASM 32.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/williamj/hst/work/cycle31/OP-cache/17460-v05.xml It is essential that the three orbits be scheduled in a coninuous block. 1747799431000 234.8832537394299 (Tic-Visit :proposal-id 17460 :visit-id "05" :proposal-version -1 :trans-version "20240604" :date "11-Jun-2024 13:33:46.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1165888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17460 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17460 :visit-id "05" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2463 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "05" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "05" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 578 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2906 :pcs-gap 0 ) false 3 0 Phase windows are not calculated when the gap between schedulable intervals is less than 1 days, assuming no scheduling restrictions for constraint Phase 0.898/0.908. The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /System/Volumes/Data/solaris/user1/williamj/hst/work/cycle31/OP-cache/17460-v55.xml It is essential that the three orbits be scheduled in a coninuous block. HOPR repeat of visit 5. (Tic-Visit :proposal-id 17460 :visit-id "55" :proposal-version -1 :trans-version "20250624" :date "30-Jul-2025 08:48:06.0" :trans-errors '(:WARNINGS 2 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 1165888 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17460 :visit-id "55" :obset-id "55" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17460 :visit-id "55" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2463 :al-overhead-at-end 0 :internal-dur-at-end 178 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2868 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "55" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 316 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2868 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17460 :visit-id "55" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2514 :al-overhead-at-end 0 :internal-dur-at-end 578 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2868 :pcs-gap 0 ) true 3 2