0Assigned ID: 1115
----- Attempting Submission 1 (Mon Sep 23 22:48:12 GMT 2019) -----In this resubmission I have NOT updated the orbital elements since there is nothing new from JPL since visit 9. The background star fields are again very crowded so I provide several relatively clear BETWEEN windows to choose from for scheduling -- Max Mutchler-1533093335----- Attempting Submission 1 (Sun Nov 03 19:25:12 GMT 2019) -----
----- Attempting Submission 2 (Thu Nov 21 17:08:09 GMT 2019) -----
----- Attempting Submission 3 (Thu Nov 21 17:56:34 GMT 2019) -----
----- Attempting Submission 4 (Tue Jan 07 16:34:03 GMT 2020) -----
----- Attempting Submission 5 (Tue Jan 07 18:26:57 GMT 2020) -----
----- Attempting Submission 6 (Tue Jan 14 20:26:39 GMT 2020) -----
----- Attempting Submission 7 (Mon Feb 10 22:08:51 GMT 2020) -----
----- Attempting Submission 8 (Tue Mar 10 15:32:05 GMT 2020) -----I get no errors or warningsInterstellar Comet C/2019 Q4 (Borisov)C/2019 Q4 (Borisov) is the first interstellar comet and only the second interstellar object ever identified within the solar system. We propose high resolution observations with WFC3 and HST in order to probe the development of this body in the post-perihelion, mid-cycle period ending March 31. In three orbits, we will map the coma and tail from a variety of perspectives in order to constrain the nucleus and dust properties. Observation as the Earth passes through the projected orbit plane (January 29) will provide a model-free estimate of the dust extent perpendicular to the plane, allowing a determination of the normal component of the dust ejection velocity. Additional observations at monthly intervals provide perspectives up to 13 degree above the orbit plane. The high resolution of HST is needed to isolate faint near-nucleus structures (jets, fans), to search for fragments of the type which accompany the appearance of many long-period (solar system) comets, and to photometrically separate the nucleus itself from the background coma. The proposed observations complement GO/DD 16009 by extending the temporal coverage of the evolution of this unique object and taking advantage of new perspectives. The comet is expected to soon become invisible as it moves rapidly away from perihelion: Q4 will pass Jupiter's distance in July 2020 and Saturn's seven months later.We request 3 mid-cycle orbits with WFC3 and the F350LP filter to image C/2019 Q4. The broad F350LP filter (effective center ~6230A, FWHM ~4760A) gives maximum sensitivity to faint coma. The three orbits would be spaced by about one month (nominally late January, February and March) giving coverage complementary to that expected from GO 16009. These orbits will provide additional perspectives on the dust distribution, needed to limit the dust properties. In addition, these orbits will enable measurement of longer-term changes in this unique target. We will secure six 260 s integrations in each orbit, with dithering to provide protection from chip defects. According to the WFC3 ETC, a single exposure of this length reaches V = 26.5 at SNR = 5. Combing 6 images will take us 1 magnitude fainter and will also provide protection from cosmic ray strikes on individual images. Deep imaging is needed to assess the near-nucleus environment and identify fragments, or set limits to their presence. We will also use individual images to examine photometric stability of the core on the (~1 hour) orbital timescale. Sub-pixel astrometry from all orbits will assist with orbit fitting and the search for non- gravitational acceleration. The current 1 sigma ephemeris uncertainty is under 1 arcsec but grows rapidly with time. This is not a problem for the proposed observations because, as with all high profile targets, continuous additions to the astrometric database by astronomers around the world will shrink this uncertainty month-by-month. The ephemeris accuracy for HST observations is expected to remain at the 1 sigma = 1 arcsec level, of no concern to these observations. Q4 is outside the 55 deg HST exclusion zone from UT 2019 October 10 until UT 2020 October 9, encapsulating the entire proposal period. We request a single-orbit observation at orbit plane crossing on January 29. This will provide a unique viewing geometry with strong diagnostic power. Motions of dust perpendicular to the orbit cannot be induced by radiation pressure and instead give a direct measure of the normal component of the ejection velocity. This observation would also fall slightly less than 1 month from the last scheduled DDT observation January 7, continuing the approximately monthly sampling of the near-nucleus environment. The second orbit is requested one month later, near February 29. The observatory will then be 9 degrees above the orbit plane, giving a perspective on the two-dimensional distribution of dust over the plane. The third orbit is requested near March 31, by which time Q4 will be outbound at 3.4 AU from the Sun (greater than the discovery distance) and we will be near the maxmum 13 degrees above the orbit plane. The first visit is the only orbit for which the constraint is tight: we need to be within 1 day of January 29.0 in order to attain the in-plane geometry and the closer to this time the better. The next two visits are more flexible; being within about +/- 7 days is sufficient.David Jewitt has experience with ground-based and space-based astronomical study of small bodies. He has led numerous past HST proposals and is lead author on 18 refereed publications about his HSt studies. Hal Weaver is a long-term comets expert, both using HST and in-situ investigations with spacecraft. Max Mutchler provides expert advice about HST operations, enabling us to extract the maximum science from the data. Jessica Agarwal and Yoonyoung Kim, both ESA investigators, provide dust dynamics expertise needed to interpret the morphology. Man-To Hui developed and quantified a profile fitting algorithm with which we will isolate the nucleus signal. We have all worked together as a well-oiled machine in previous leading-edge studies.Solar System6falsefalsefalsefalsefalsefalsefalseSUPPORTEDSOLAR SYSTEMYESCOMETInterstellar cometTYPE=COMET,Q=2.006616039924964,E=3.35705587897315,I=44.05351923993201
,O=308.1499849748581,W=209.1244471001688,T=08-DEC-2019:13:18:19,TTimeScale=TDB,EQUINOX=J2000,EPOCH=05-JAN-2020:00:00:00,EpochTimeScale=TDB,A1=-4.515200138092E-8,A2=-3.231415748596E-8,A3=-1.17710609436E-7EARTHSOLAR SYSTEMYESCOMETInterstellar cometTYPE=COMET,Q=2.006615476559197,E=3.357057274677898,I=44.05348671638512
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