0 Assigned ID: 4275 ----- Attempting Submission 1 (Wed May 24 08:06:42 GMT 2023) ----- HST Phase I Proposal 4275 successfully submitted. Receipt: # 4275-1 ----- Attempting Submission 2 (Wed May 24 20:34:23 GMT 2023) ----- HST Phase I Proposal 4275 successfully submitted. Receipt: # 4275-2 ----- Attempting Submission 3 (Wed May 24 23:57:38 GMT 2023) ----- 0 High-resolution imaging of Fomalhaut's newly discovered intermediate dust belt to precisely measure the planetary system geometry The dusty debris belts surrounding the nearby star Fomalhaut show indirect evidence for hidden planets gravitationally sculpting the system. Fomalhaut has been studied by every major observatory and interpreted through many theory papers, demonstrating wide interest by the astronomical community. The most recent breakthrough comes from JWST/MIRI images that reveal the existence of an intermediate dust belt at ~100 au not previously seen in any other data set. Here we show that the intermediate belt can be detected in dust-scattered light in archival STIS data. However, these observations used a subarray that limited the detection to roughly 90 degrees along the belt's minor axis. Here we propose new observations that increase both the field of view and integration time to map the entire intermediate belt in dust-scattered light. These data will exceed JWST/MIRI's angular resolution by a factor of seven and enable a precise measurement of the belt's geometric properties. The results will show to what extent the intermediate belt is misaligned with the inner asteroid belt analog and the outer belt. Its stellocentric offset will be measured to the same precision as the outer belt, and the radial gap between belts will give theorists more precise information on modeling the properties of hypothesized planets inferred to exist between the belts. The goal is to image Fomalhaut's intermediate dust belt, which is expected to be brightest along its eastern hemisphere (PA~0-180), which is the forward scattering direction. For PSF subtraction we have two PSF reference stars Vega and Theta Peg that will be observed at any ORIENT before and after three orbits of Fomalhaut observations. Each Fomalhaut observation has ORIENT constraints and ORIENT FROM commands in order to roll the telescope up to 30 degrees. The ORIENT constraints are chosen so that as much of the intermediate belt is imaged given that the STIS occulting wedge and diffraction spikes are blocking a large fraction of the field of view. All observations will be made with the stars acquired behind WEDGEB2.0. Integration times are chosen so as not to saturate the pixels close to the edge of the wedge. In order to maximize the total integration time, we use a subarray of 700 pixels to reduce readout times. In order to perform PSF subtraction using the PSF reference stars, the first group of five VISITS (i.e. orbits) should be executed consecutively, without interruptions, so that the PSF variations from orbit to orbit are minimized. To achieve this we use a SEQUENCE constraint starting from Visit 01. The same procedure is implemented for the second group of five VISITS (05-10) with the sequence command starting from Visit 05. The PSF reference stars also have an ORIENT FROM command so that Vega in Visit 01 is not imaged at exactly the same ORIENT in Visit 06, and likewise with theta Peg. If there are background stars in the field we would prefer to have them moved to different detector positions between each pair of orbits. Jason Wang, Michael Fitzgerald, Dr. Robert De Rosa, and Max Millar-Blanchaer are experts in high contrast imaging observations, data reduction techniques, and precision astrometry. Paul Kalas specializes in the science of debris disks and exoplanets, with expertise in high-contrast imaging methods (observations, data reduction, and analysis) using all of HST's past and present imaging cameras. He has extensive experience designing large and long-term science programs, managing teams spread over multiple institutions, and mentoring graduate students and postdocs. Mark Wyatt and Grant Kennedy both have extensive experience analyzing and interpreting debris disk data from the optical (e.g., HST) to the millimeter (e.g., ALMA). They are recognized as leaders in the theoretical understanding of debris disks and planet-disk interactions and will lead the theory effort of our science program. Exoplanets and Exoplanet Formation 6 false false false false false false false SUPPORTED STAR A4-A9 V-IV DISK EXTRA-SOLAR PLANETARY SYSTEM This object was generated by the targetselector and retrieved from the SIMBAD database. FOMALHAUT J2000 J2000 STAR A0-A3 V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. VEGA J2000 J2000 STAR A0-A3 V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 STIS/CCD Imaging Yes No WEDGEB2.0 STIS/CCD Imaging Yes No WEDGEB2.0 STIS/CCD Imaging Yes No WEDGEB2.0 STIS/CCD Imaging Yes No WEDGEB2.0 STIS/CCD Imaging Yes No WEDGEB2.0 Timing link suitability includes constraints ([Sequence (01 02 03 04 05) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "01" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:19:10.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2555 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2868 :pcs-gap 0 ) false 1 1 Timing link suitability includes constraints ([Sequence (01 02 03 04 05) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "02" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:19:12.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "02" :orbit-number 1 :pcs-time 301 :si-vis-utilization 2605 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2864 :pcs-gap 0 ) false 1 1 Timing link suitability includes constraints ([Sequence (01 02 03 04 05) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "03" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:21:54.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "03" :orbit-number 1 :pcs-time 301 :si-vis-utilization 2605 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2864 :pcs-gap 0 ) false 1 1 Timing link suitability includes constraints ([Sequence (01 02 03 04 05) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "04" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:21:55.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "04" :orbit-number 1 :pcs-time 301 :si-vis-utilization 2605 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3031 :pcs-gap 0 ) false 1 0 Timing link suitability includes constraints ([Sequence (01 02 03 04 05) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "05" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:07:40.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 431696 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "05" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2547 :al-overhead-at-end 0 :internal-dur-at-end 327 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2977 :pcs-gap 0 ) false 1 0 Timing link suitability includes constraints ([Sequence (06 07 08 09 10) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "06" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:07:41.0" :trans-errors '(:WARNINGS 44 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "06" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2555 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2992 :pcs-gap 0 ) false 1 0 Timing link suitability includes constraints ([Sequence (06 07 08 09 10) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "07" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:19:14.0" :trans-errors '(:WARNINGS 45 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "07" :obset-id "07" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "07" :orbit-number 1 :pcs-time 301 :si-vis-utilization 2605 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2864 :pcs-gap 0 ) false 1 1 Timing link suitability includes constraints ([Sequence (06 07 08 09 10) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "08" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:19:16.0" :trans-errors '(:WARNINGS 45 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "08" :obset-id "08" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "08" :orbit-number 1 :pcs-time 301 :si-vis-utilization 2605 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2864 :pcs-gap 0 ) false 1 1 Timing link suitability includes constraints ([Sequence (06 07 08 09 10) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "09" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:19:17.0" :trans-errors '(:WARNINGS 45 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 542576 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "09" :obset-id "09" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "09" :orbit-number 1 :pcs-time 301 :si-vis-utilization 2605 :al-overhead-at-end 0 :internal-dur-at-end 446 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2864 :pcs-gap 0 ) false 1 1 Timing link suitability includes constraints ([Sequence (06 07 08 09 10) within 0.3 days]) The scheduling data was generated by CASM 34.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 17459 :visit-id "10" :proposal-version -1 :trans-version "20250929" :date "17-Feb-2026 19:19:18.0" :trans-errors '(:WARNINGS 36 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 431696 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17459 :visit-id "10" :obset-id "10" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17459 :visit-id "10" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2547 :al-overhead-at-end 0 :internal-dur-at-end 327 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2867 :pcs-gap 0 ) false 1 1