0 Assigned ID: 84 ----- Attempting Submission 1 (Mon Mar 02 17:53:33 GMT 2020) ----- HST Phase I Proposal 84 successfully submitted. Receipt: # 84-1 ----- Attempting Submission 2 (Fri Mar 06 21:23:03 GMT 2020) ----- ORBITAL VISIBILITY OVERRUN ORBITAL VISIBILITY OVERRUN ORBITAL VISIBILITY OVERRUN ORBITAL VISIBILITY OVERRUN In this resubmission I have checked the box for No Gyro Bias Update (rather than have to reduce exposure times) for visit 5 since it is just one orbit. -- Max Mutchler -703469951 ----- Attempting Submission 1 (Mon Jun 15 21:36:16 GMT 2020) ----- ----- Attempting Submission 2 (Mon Sep 14 20:01:46 GMT 2020) ----- ----- Attempting Submission 3 (Tue Nov 10 16:07:33 GMT 2020) ----- ----- Attempting Submission 4 (Mon Mar 01 15:22:13 GMT 2021) ----- ----- Attempting Submission 5 (Fri May 14 17:47:31 GMT 2021) ----- HST Phase II Proposal 16309 failed submission. ----- Attempting Submission 6 (Fri May 14 17:57:09 GMT 2021) ----- ----- Attempting Submission 7 (Fri Aug 13 14:19:26 GMT 2021) ----- ----- Attempting Submission 8 (Wed Aug 18 13:54:04 GMT 2021) ----- The orbital overrun warnings only apply retroactively to the already-executed visits. Long-Period Comet C/2017 K2 Extraordinary long-period comet C/2017 K2 offers our best opportunity to study the rise of activity in a body entering the solar system from Oort cloud distances. Active initially at 26 AU, the comet is now near 8 AU and will approach the nominal distance for the onset of water ice sublimation by the end of Cycle 28. We seek HST observations 1) to measure the 3D morphology of the coma and to search for jet activity associated with local crystallization 2) to photometrically isolate the nucleus from its massive coma background and so to estimate its size and 3) to contribute to a unique record of cometary development from the largest distances. Already active when first detected beyond Uranus, K2 will cross both the crystallization zone (10 AU) and the water ice sublimation zone (5 AU) on its way to perihelion at 1.8 AU in late 2022. It is predicted to exceed naked-eye visibility and will be subject to increasingly intense astronomical study using the full range of techniques and wavelengths. It offers a unique opportunity to understand the degree to which comets evolve even before entry into the terrestrial planet region where they are more normally studied. We request 5 orbits with WFC3 to study K2 on approach to the water sublimation zone. The proposed observations will be the first to examine an approach to the Sun from far beyond the planetary region. WFC3-UVIS and the F350LP filter provide maximum sensitivity to faint and structured emission. In each orbit, we will obtain 6 images each of 285s duration, with a dither between groups of three in order to provide protection from chip and flat-field defects. Combination of the images allows the elimination of essential all cosmic ray tracks that otherwise would compromise the measurements. Our science objectives follow. Objective 1: Determine the photometric and morphological changes occurring as K2 enters the range of distances where water sublimation is expected to begin. Published observations (Jewitt et al. 2017, 2019) establish the status at larger distances (13 to 16 AU). They reveal a massive (1010 kg), slowly expanding (4 m/s), spherical coma of submillimeter and larger grains unlike anything expected from standard models. We want to observe the evolution of this coma with time, both due to the action of radiation pressure and to the injection of fresh material at the center, especially that expected from the onset of water ice sublimation, in addition to continued activity from the supervolatiles. Deflection of the dust by radiation pressure allows us to make comparison with dust dynamics models to estimate dust parameters. We want to know to what extent the changes in K2 represent the loss of supervolatile interstellar frosting as opposed to other physical processes in the nucleus. We expect to detect bursty activity from the expelled gas, brightening near the nucleus, and a sudden steepening of the coma surface brightness relative to its value at larger rH (Jewitt et al. 2019). Localized activity will also produce near-nucleus jets, in stark contrast to the spherical coma evident in existing data. In order to optimally extract information about the dust coma of K2, we plan measurements as follows. Visit 1 is scheduled as early as possible to assess the initial state of the comet in Cycle 28, and will permit comparisons with existing imaging data (Cycle 27 data will become public in 2020 April). Visit 2 observes the comet as the Earth crosses its orbit plane from north to south. This in-plane geometry provides special sensitivity to the largest particles, whose low ejection speeds confine them to the cometary orbit plane, giving a line-line tail or trail appearance. The thickness of this line is a direct measure of the ejection speed, and a primary constraint on the ejection mechanism. Visit 3 is timed to image K2 from the largest angle below the orbital plane. This provides the best perspective on the distribution of material in the plane, and we expect to detect the first fan-like tail in K2 owing to ongoing mass-loss. New material from sublimation activity will reveal itself by its spatial distribution in the plane (c.f. Finson & Probstein 1968). Visit 4 again records the comet from its orbital plane but as the Earth moves from south to north, about 6 months after the first plane-crossing and at rH = 6 AU instead or 7.5 AU. Comparison with Visit 2 will allow us to assess changes from exactly the same viewing angle. Visit dates within 2 to 3 days are desirable. Final Visit 5 occurs from the maximum angle above the orbital plane, providing a stereo view when compared with Visit 3. This combination of times and angles will give us maximum leverage in the application of our dust dynamics model, needed to extract fundamental parameters of the coma. Objective 2: Isolate the nucleus from the adjacent dust coma to estimate its size. This must be done using a convolution coma model to interpret the innermost surface brightness profile and to subtract off the effects of the coma. This is an extremely challenging measurement, but attempts with existing data hint at a nucleus detection with an upper limit radius < 9 km. Knowing the nucleus radius is important for understanding the relation between size and activity level, and may impact the evolution and survival of the nucleus. Small nuclei, for instance, are much more susceptible to non-gravitational acceleration and spin-up torques than are large nuclei. The size may also foretell the brightness to be expected of this comet at perihelion in 2022. Our observing strategy is to take WFC3 exposures using a wide bandpass filter (F350LP) for maximum sensitivity. The predicted brightness of a 9 km nucleus in the range 8.0 AU to 5.2 AU is V = 21.8 to 19.9 which would be trivial to detect in the absence of coma. However, given the presence of the massive coma, and the reality that 9 km is an upper limit to the nucleus radius (Jewitt et al. 2017), we cannot hope to isolate the nucleus without the fine resolution and PSF stability of HST and may not be able to do so even then. In order to attain the maximum resolution, we will perform a subsampling dither box pattern, obtaining 2 exposures at each dither point. We will carefully drizzle our subsampled images to a finer output pixel scale (0.025 arcsec/pixel) to extract the extra spatial information gathered by our subsampling strategy. This enhanced resolution (0.067 arcsec FWHM) will allow us to improve the nucleus vs. coma contrast over what is possible from the ground by about a factor of 50. The dithering will also enable us to reject hot pixels and cosmic ray hits. The team has expertise in all aspects of the program, including physics of active asteroids, origin of active asteroids, dynamics of dust under the action of radiation and gravity, operational details of HST, reduction and analysis of WFC3 data and prompt publication of the data. David Jewitt has an extensive record of research into the study of small solar system bodies, especially the Kuiper belt objects and the cometary nuclei. In the last decade he has written 20 refereed papers based on Hubble data. Max Mutchler is an expert in planning the aquisition of HST data and interpreting its properties. Jessica Agarwal and Yoonyoung Kim are experts in modeling the dynamics of dust under the combined action of solar gravity and radiation pressure, with experience in the application to many comets. Jing Li is experienced in CCD data reduction techniques. Harold Weaver is a long-term user of HST with experience in all aspects of its operation. Man-To Hui is experienced in the observational study of comets and in interpretation of surface brightness photometry. We will all cooperate to promptly write the papers. Solar System Astronomy 6 false false false false false false false false SUPPORTED SOLAR SYSTEM YES COMET distant comet TYPE=COMET,Q=1.80336386311596,E=1.00036668185704,I=87.54144075815482 ,O=88.2703559960372,W=236.1075587592327,T=20-DEC-2022:09:46:55,TTimeScale=TDB,EQUINOX=J2000,EPOCH=23-MAY-2019:00:00:00,EpochTimeScale=TDB EARTH SOLAR SYSTEM YES COMET distant comet TYPE=COMET,Q=1.802802851169086,E=1.000370469000311,I=87.54131033034835 ,O=88.27093088001131,W=236.1149816010203,T=20-DEC-2022:08:14:46,TTimeScale=TDB,EQUINOX=J2000,EPOCH=11-JUL-2019:00:00:00,EpochTimeScale=TDB EARTH SOLAR SYSTEM YES COMET distant comet TYPE=COMET,Q=1.802496797977771,E=1.000372873245172,I=87.54124199211779 ,O=88.27121986972777,W=236.1190668008936,T=20-DEC-2022:07:24:39,TTimeScale=TDB,EQUINOX=J2000,EPOCH=08-AUG-2019:00:00:00,EpochTimeScale=TDB EARTH SOLAR SYSTEM YES COMET distant comet TYPE=COMET,Q=1.802002642886023,E=1.000374482326085,I=87.54106073961911 ,O=88.27195428426677,W=236.1258629200095,T=20-DEC-2022:06:06:37,TTimeScale=TDB,EQUINOX=J2000,EPOCH=21-SEP-2019:00:00:00,EpochTimeScale=TDB EARTH SOLAR SYSTEM YES COMET distant comet TYPE=COMET,Q=1.800557446902831,E=1.000385549098293,I=87.54218835728831 ,O=88.26798465637555,W=236.1463652133023,T=20-DEC-2022:02:24:53,TTimeScale=TDB,EQUINOX=J2000,EPOCH=08-FEB-2020:00:00:00,EpochTimeScale=TDB EARTH WFC3/UVIS Imaging No No F350LP POS-TARG DITHER 2.4 LINE false false 2 86 LINE 3 false POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 4 false Using ephemeris for target 16309-01-C2017-K2 ephemeris data for target 16309-01-C2017-K2 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 20.250 to 22.213. ephemeris interval: 21.212 to 23.213 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. /private/var/folders/tj/27ygn_756lz3w1z19s6wtgtm0006vh/T/OPVisit10844907883751920850.xml 1601971258000 68.7128052881354 (Tic-Visit :proposal-id 16309 :visit-id "01" :proposal-version -1 :trans-version "20210514" :date "18-Aug-2021 09:49:44.0" :trans-errors '(:WARNINGS 1 :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 859040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16309 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16309 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2710 :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 2782 :pcs-gap 0 ) true 1 1 Using ephemeris for target 16309-02-C2017-K2-2 ephemeris data for target 16309-02-C2017-K2-2 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 20.250 to 22.213. ephemeris interval: 21.212 to 23.213 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. /private/var/folders/tj/27ygn_756lz3w1z19s6wtgtm0006vh/T/OPVisit6632297597406158928.xml 1608331131000 359.1548731961907 (Tic-Visit :proposal-id 16309 :visit-id "02" :proposal-version -1 :trans-version "20210514" :date "18-Aug-2021 09:49:44.0" :trans-errors '(:WARNINGS 1 :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 859040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16309 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16309 :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 2782 :pcs-gap 0 ) true 1 1 Using ephemeris for target 16309-03-C2017-K2-3 ephemeris data for target 16309-03-C2017-K2-3 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 20.250 to 22.213. ephemeris interval: 21.212 to 23.213 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. /private/var/folders/tj/27ygn_756lz3w1z19s6wtgtm0006vh/T/OPVisit2070871047123398782.xml 1616544187000 272.0 (Tic-Visit :proposal-id 16309 :visit-id "03" :proposal-version -1 :trans-version "20210514" :date "18-Aug-2021 09:49:45.0" :trans-errors '(:WARNINGS 1 :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 859040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16309 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16309 :visit-id "03" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2710 :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 2782 :pcs-gap 0 ) true 1 1 Using ephemeris for target 16309-04-C2017-K2-4 ephemeris data for target 16309-04-C2017-K2-4 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 20.250 to 22.213. ephemeris interval: 21.212 to 23.213 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. /private/var/folders/tj/27ygn_756lz3w1z19s6wtgtm0006vh/T/OPVisit4364962830096982240.xml 1623600589000 162.0 (Tic-Visit :proposal-id 16309 :visit-id "04" :proposal-version -1 :trans-version "20210514" :date "18-Aug-2021 09:49:46.0" :trans-errors '(:WARNINGS 1 :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 859040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16309 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16309 :visit-id "04" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2710 :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 2782 :pcs-gap 0 ) true 1 1 Using ephemeris for target 16309-05-C2017-K2-5 ephemeris data for target 16309-05-C2017-K2-5 does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 20.250 to 22.213. ephemeris interval: 21.212 to 23.213 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. /Users/mutchler/Desktop/APT/16309_K2/OP-cache/16309_k2_visit5gyro-v05.xml (Tic-Visit :proposal-id 16309 :visit-id "05" :proposal-version -1 :trans-version "20210514" :date "18-Aug-2021 09:45:36.0" :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 859040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16309 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16309 :visit-id "05" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2710 :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