0 Assigned ID: 6093 ----- Attempting Submission 1 (Thu Apr 03 14:28:46 GMT 2025) ----- HST Phase I Proposal 6093 successfully submitted. Receipt: # 6093-1 ----- Attempting Submission 2 (Thu Apr 10 23:38:33 GMT 2025) ----- First version of Phase 2 for PID 18002. We are happy to edit anything (including scheduling) as needed. -582363619 ----- Attempting Submission 1 (Thu Jul 24 18:12:22 GMT 2025) ----- Probing the Interior of the Dwarf Planet Haumea In the region beyond Neptune, a diverse population of small, icy bodies exists. These transneptunian objects (TNOs) are some of the most enigmatic bodies in our solar system. The most mysterious of these bodies is Haumea, a large (~1500 km diameter), rapidly rotating body (3.9 hours) hosting two moons (Hi'iaka and Namaka). Haumea, like most of the other large TNOs, is thought to be differentiated, with a dense, rocky core surrounded by a water-ice mantle. Between these layers, a thin subsurface ocean may have once existed, with significant astrobiological potential. Although indirect evidence indicates Haumea may be differentiated, no direct probe of Haumea's interior has yet to be made. In this program, we use astrometric tracking of Haumea's moons to infer the interior structure of Haumea. We require 3, well-timed single-orbit visits using WFC3/UVIS, which will enable detection of Haumea's differentiated core at a significance of ~3 sigma. This low-risk, high-reward program will provide the first direct probe into the interior of a TNO, acting as a touchstone for understanding the interiors of the icy transneptunian population. Our observations call for 3 single-orbit visits to image the Haumea system using the WFC3/UVIS instrument. During each visit, images will be acquired using the UVIS2-C512C-SUB aperture, paired with the F350LP filter to optimize astrometric precision. Exposure times are chosen to optimize SNR and schedulability, with 10+ dithered images taken during each visit. This allows us to remain robust to unlucky cosmic ray hits. Scheduling of observations is important to the goals of our program. The timing windows input into the Phase II are somewhat flexible, and can be changed if needed. If more observing windows are needed, we can provide them, although these are our "optimal" windows. We would prefer if each visit is at least 20 days apart, although this is not necessary. Once observations are scheduled, we are happy to check if any bright stars are too close to our targets, although Haumea is currently in a fairly empty part of the sky. Reduced gyro operations will not significantly affect the execution of this program, apart from potentially requiring a rescheduling of observations due to reductions in observing windows. As needed, we can flexibly reschedule observations without significantly harming the goals of this program. Reduced spatial scan speed will not prohibit observations of our target as the maximum needed spatial scan speed is ~5 arcseconds/hour, well within the limits of reduced gyro operations. PI Benjamin Proudfoot is a postdoctoral scholar at the University of Central Florida. He is an expert in non-Keplerian orbit fitting of TNO moons and the lead developer of the MultiMoon code, which will be used to do all orbit fitting in this investigation. He has led several past studies focusing on understanding Haumea, including the latest work on the orbits of Namaka and Hi'iaka. Co-I Ragozzine is an expert in TNO satellite orbit fitting, with extensive experience in detecting non-Keplerian effects caused by massive moons (like those of Haumea). He has been PI of multiple HST programs focusing on understanding the formation, evolution, and physical characteristics of TNOs. He was the PI/Co-I of 5+ programs to study the orbits of Haumea's moons. Co-I Grundy is a major expert in HST data reduction and analysis for TNBs. He has led several programs focusing on characterization of individual TNB systems. He maintains an extensive online catalog of TNBs. Co-I Fernandez-Valenzuela is an expert in image analysis of TNOs. She is the lead of the recent campaigns to observe occultations of Hi'iaka and Namaka, and has extensive experience analyzing occultation observations. Co-I Rommel is an expert in occultation prediction, observation, and analysis. She led the analysis of the recent occultation of Namaka. Co-I Holler is a member of the JWST/MIRI instrument team and is the JWST Solar System Deputy Lead. He is an expert in understanding and observing TNOs from a variety of facilities, both ground and space based. Solar System Astronomy 6 false false false false false false SUPPORTED SOLAR SYSTEM DWARF-PLANET Haumea STD=HAUMEA EARTH WFC3/UVIS Imaging No No F350LP WFC3/UVIS Imaging No No F350LP WFC3/UVIS Imaging No No F350LP POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false POS-TARG DITHER 0.135 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 2 false /private/var/folders/tm/bvd5g5k95vq10v9nl69qpjj80000gn/T/OPVisit4858429540399503350.xml The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. Visit to focus on Namaka's position (Tic-Visit :proposal-id 18002 :visit-id "01" :proposal-version -1 :trans-version "20250624" :date "24-Jul-2025 11:49:18.0" :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 100688 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18002 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18002 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2591 :al-overhead-at-end 0 :internal-dur-at-end 147 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 0 /private/var/folders/tm/bvd5g5k95vq10v9nl69qpjj80000gn/T/OPVisit1100418742869175743.xml The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. Visit to focus on both moons (Tic-Visit :proposal-id 18002 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "24-Jul-2025 12:02:49.0" :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 100688 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18002 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18002 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2591 :al-overhead-at-end 0 :internal-dur-at-end 147 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 0 /private/var/folders/tm/bvd5g5k95vq10v9nl69qpjj80000gn/T/OPVisit10862238634164357193.xml The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. Visit to focus on the secondary uncertainty peak (Tic-Visit :proposal-id 18002 :visit-id "03" :proposal-version -1 :trans-version "20250624" :date "24-Jul-2025 12:02:51.0" :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 100688 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 18002 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 18002 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2591 :al-overhead-at-end 0 :internal-dur-at-end 147 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 0