Colors and Astrometry of Two New Horizons Target Scattered Disk Objects

Initial Submission -855350808 Assigned ID: 2680 ----- Attempting Submission 1 (Mon Jan 31 18:13:02 GMT 2022) ----- HST Phase I Proposal 2680 successfully submitted. Receipt: # 2680-1 FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser FLASH level may be too low for this exposure or a short subexposure. See extended explanation in the diagnostic browser Update with BETWEEN windows added to avoid close stars for July observations. -154559243 ----- Attempting Submission 1 (Tue Mar 29 14:40:19 GMT 2022) ----- HST Phase II Proposal 16924 successfully submitted. Receipt: # 16924-1 ----- Attempting Submission 2 (Fri Apr 22 22:05:32 GMT 2022) ----- ----- Attempting Submission 3 (Tue Jul 12 17:54:46 GMT 2022) ----- Exposures are required to be this short to minimize confusion with cosmic rays, and are as long as possible within the windows. Colors and Astrometry of Two New Horizons Target Scattered Disk Objects This program would observe two low-inclination Scattered Disk Objects (SDOs) with five total orbits to measure their color and astrometry. These SDOs, 2020 KS11 and 2020 KV11, are both potential future targets for observation by NASA's New Horizons spacecraft. Their colors would be measured with WFC3/UVIS and two filters (F606W and F814W) to both compare their colors to other past New Horizons, targets and to provide some of the first measurements of the colors of low-inclination SDOs. Low-inclination SDOs are relatively rare in the scattered disk population, and previous ground-based color investigations were only able to measure colors for an even smaller fraction of those. The proposed observations would measure the colors of fainter and smaller SDOs than are possible to measure from the ground, helping to understand this curious population. The proposed observations are critical to be performed in Cycle 29, as additional HST astrometry is required to improve their orbits sufficiently to allow New Horizons them, and the sooner that astrometry is available, the sooner that the New Horizons project can plan those observations. The proposed observations would improve the orbit of 2020 KS11 more than is possible with ground-based telescopes before it would be observed by New Horizons in 2024, and would provide as much improvement in the orbit of 2020 KV11 as eight semesters of ground-based data. These targets were not previously proposed to be observed in Cycle 29, as the Cycle 28 observations of them were required first to know that they were good targets for New Horizons, and to know what quantity of additional HST astrometry would be required. Two targets are to be observed in this program: 2020 KS11 with two orbits and 2020 KV11 with three orbits, both using using two filters, for a total request of five orbits. All of the observations for this program would follow the model established by prior successful HST astrometric observations of KBOs in support of New Horizons, GO-12535, GO-12887, GO-14092, GO-15108, and GO-16183. Each orbit consists of five >350 second observations with WFPC3. The ''No Gyro Bias Update on Moving Target'' special requirement is selected to maximize observation time, as all our observations are single orbits. This provides sufficiently deep observations to be able to recover the target KBOs in individual images, while also providing sufficient redundancy to cosmic rays. Please note that we used the auto-adjust in Orbit Planner to maximize the the exposure times, which reduced the observation windows in Visit Planner. If those windows are too small, we would be fine with reducing the exposure times to 350 seconds to increase schedulability. The five exposures would use the full UVIS1 and UVIS2 chips, with the target nominally centered on UVIS2, and a five-point line dither over the course of the orbit to minimize per-pixel effects. The first two observations would be with the F606W filter, and the second three with the F814W, following the example of GO-14092. The proposed targets must be observed between mid-April 2022 and the start of September 2022 to ensure that their apparent sky motion is high enough for them to be reliably recovered. Preferably, the two 2020 KS11 orbits and the first two 2020 KV11 orbits would be in June 2022, and the remaining 2020 KV11 orbit in August 2022. This strategy provides time enough that if the June observations are unsuccessful due to the guide star failing to lock or any other issue, they could be repeated via HOPR in the second half of the observation window. If both the June and August observations are successful, then the parallax between them would provide a better constrain than observations that were all in one month. This parallax effect is particularly useful for 2020 KV11, and would increase the probability that it is in the New Horizons LORRI planning window from 79% to 98%. Observations before June would have lower SNR due to their higher Sun-Target-Observer phase angle, which would reduce the quality of the color measurements. The observations in this proposal therefore assume a 50% failure rate in executing observations due to guide star acquision failures to reach our minimum success for astrometric improvement, and the observations are front-loaded towards the start of the observing window, to provide maximum time to repeat any observations with a HOPR. At least two orbits are preferable to measure color, to minimize any rotational lightcurve effects. We request to check the background fields once scheduling windows for HST are chosen to ensure that there are no background stars which would compromise the observations. Dr. Simon Porter is a New Horizons CoI, and is an expert in the astrometric observation of KBOs with HST and New Horizons. Dr. Susan Benecchi is a New Horizons CoI, and is an expert in the measurement of colors of KBOs with HST. Dr. Wesley Fraser is a New Horizons Collaborator, and is the PI of the Col-OSSOS program that has provided the first colors for faint SDOs. Dr. Anne Verbiscer is a New Horizons Assistant Project Scientist, and is an expert in the analysis of KBO solar phase curves with HST and New Horizons. Dr. John Spencer is a New Horizons Deputy Project Scientist, is the lead for planning KBO science observations for New Horizons, and is an expert in KBO science. Dr. Marc Buie is a New Horizons CoI, is the lead of distant KBO science for the New Horizons mission, and is an expert in KBO astrometry with HST. Dr. Alan Stern is PI of the New Horizons mission an expert in KBO science. Solar System Astronomy 0 false false false false false true false SUPPORTED SOLAR SYSTEM ASTEROID 2020 KS11 TYPE=ASTEROID,A=99.873078869803,E=0.648998146332,I=2.663245886817,O=169.007102043507,W=27.219744134456,M=21.856781947501,EQUINOX=J2000,EPOCH=15-JUL-2022:00:00:00,EpochTimeScale=UTC EARTH SOLAR SYSTEM ASTEROID 2020 KV11 TYPE=ASTEROID,A=95.493051218105,E=0.621225667767,I=4.624574479235,O=135.155110306248,W=50.267700440368,M=29.708118547190,EQUINOX=J2000,EPOCH=15-JUL-2022:00:00:00,EpochTimeScale=UTC EARTH WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W CELESTIAL OTHER 0.75 LINE false true 2 0 LINE 1

false

CELESTIAL OTHER 0.75 LINE false true 3 0 LINE 2

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1657648337522 Using ephemeris for target 16924-01-2020KS11 ephemeris data for target 16924-01-2020KS11 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 22.120 to 23.182. ephemeris interval: 22.181 to 24.183 The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. We request to check the background field once scheduling windows for HST are chosen to ensure that there are no background stars which would compromise the observation. 1654013579000 259.441074199398 (Tic-Visit :proposal-id 16924 :visit-id "01" :proposal-version -1 :trans-version "20220516" :date "12-Jul-2022 11:52:17.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1443744 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16924 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16924 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2606 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 1657648338005 Using ephemeris for target 16924-02-2020KS11 ephemeris data for target 16924-02-2020KS11 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 22.120 to 23.182. ephemeris interval: 22.181 to 24.183 The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. We request to check the background field once scheduling windows for HST are chosen to ensure that there are no background stars which would compromise the observation. (Tic-Visit :proposal-id 16924 :visit-id "02" :proposal-version -1 :trans-version "20220516" :date "12-Jul-2022 11:52:17.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1443744 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16924 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16924 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2606 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 1657648338513 Using ephemeris for target 16924-03-2020KV11 ephemeris data for target 16924-03-2020KV11 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 22.120 to 23.182. ephemeris interval: 22.181 to 24.183 Timing link suitability includes constraints ([04 After 03 by 7.0 to 1000000000.0 days]) The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. We request to check the background field once scheduling windows for HST are chosen to ensure that there are no background stars which would compromise the observation. 1654099272000 259.8355903006889 (Tic-Visit :proposal-id 16924 :visit-id "03" :proposal-version -1 :trans-version "20220516" :date "12-Jul-2022 11:52:18.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1443744 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16924 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16924 :visit-id "03" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2606 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 1657648338946 Using ephemeris for target 16924-04-2020KV11 ephemeris data for target 16924-04-2020KV11 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 22.120 to 23.182. ephemeris interval: 22.181 to 24.183 Timing link suitability includes constraints ([04 After 03 by 7.0 to 1000000000.0 days]) The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. We request to check the background field once scheduling windows for HST are chosen to ensure that there are no background stars which would compromise the observation. 1654950851000 260.5 (Tic-Visit :proposal-id 16924 :visit-id "04" :proposal-version -1 :trans-version "20220516" :date "12-Jul-2022 11:52:18.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1443744 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16924 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16924 :visit-id "04" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2606 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 1657648339373 Using ephemeris for target 16924-05-2020KV11 ephemeris data for target 16924-05-2020KV11 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 22.120 to 23.182. ephemeris interval: 22.181 to 24.183 The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. We request to check the background field once scheduling windows for HST are chosen to ensure that there are no background stars which would compromise the observation. (Tic-Visit :proposal-id 16924 :visit-id "05" :proposal-version -1 :trans-version "20220516" :date "12-Jul-2022 11:52:19.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1443744 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16924 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16924 :visit-id "05" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2606 :al-overhead-at-end 0 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0