This is a proposal in support of the NASA New Horizons mission. 1521227634 Assigned ID: 1635 ----- Attempting Submission 1 (Fri Feb 09 22:18:01 GMT 2018) ----- This revision includes shifting the scheduling window forward by one week, slightly shorter exposure on the short exposures (16s down to 15s), and a slightly faster scan rate to address potential saturation issues. -1212705105 ----- Attempting Submission 1 (Fri Mar 23 13:53:29 GMT 2018) ----- ----- Attempting Submission 2 (Thu Apr 05 21:20:03 GMT 2018) ----- We propose observations in support of the upcoming New Horizons encounter for 2014MU69. One visit is for support observations of a star to be occulted by 2014MU69 on 2018 August 4 from which ultra-precise astrometry and shape information about the target can be derived. The second visit is for a backup epoch of astrometry on 2014MU69 itself at the end of the 2018 observing window at a time when New Horizons will also be observing the target. The two visits in this program are very different. One visit is a routine observation of 2014MU69 for astrometry and uses the same observing methods we have been using since 2014. Five long exposures, full field with WFC3, tracking 2014MU69. This visit needs to be coordinated with the last visit of the multi-cycle proposal started with proposal id 14629. The two visits will need to be scheduled about three days apart in October 2018. These will be the last HST data prior to the New Horizons encounter with 2014MU69. The second visit is of a star that will be occulted by 2014MU69 on 2018 August 4. These observations are primarly intended to check for stellar duplicity that, if found, would provide a crucial update to the occultation prediction. These images also are used to get near-epoch observatoins of the occultation star for an improved position over what we have from the Gaia DR2 catalog. The observations consist of short sub-array exposures with dithering to reconstruct a diffraction limited image and a smaller number of full-field images for astrometry of the target star. Solar System 0 false SUPPORTED STAR UNDESIGNATED J2000 J2000 SOLAR SYSTEM ASTEROID Kuiper-Belt Object TYPE=ASTEROID,A=44.522607562638,E=0.040269637522,I=2.452265958242,O=158.963182412558,W=174.926199040395,M=315.140003030700,EQUINOX=J2000,EPOCH=15-AUG-2018:00:00:00,EpochTimeScale=UTC EARTH WFC3/UVIS Imaging No No F350LP WFC3/UVIS Imaging No No F350LP WFC3/UVIS Imaging No No F475W CELESTIAL OTHER .030 Objects will naturally dither themselves in a predominantly east-west direction. This dither pattern uses offsets perpendicular to the mean motion of the objects with a two-level pattern so that the dither cannot lead to a false detection with coherent motion. The overall pattern is six positions with 0.75 pixel spacing. LINE false true 5 0 LINE 1 false POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 2 false 1521752800257 Using ephemeris for target 15450-13-486958-E ephemeris data for target 15450-13-486958-E does not cover planning interval. Physical constraints are assumed to be unschedulable outside of the ephemeris data. Planning interval: 17.213 to 19.091. ephemeris interval: 18.090 to 20.092 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. The scheduling for this visit must be coordinated with visit 12 from (14629/15158/?????). These two visits are to be sheduled three days apart within the same one week window. We will need to verify the scheduling window for each visit to ensure there are no field star contamination problems. (Tic-Visit :proposal-id 15450 :visit-id "13" :proposal-version -1 :trans-version "20171009" :date "22-Mar-2018 15:06:40.0" :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 15450 :visit-id "13" :obset-id "13" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15450 :visit-id "13" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2656 :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 3002 :pcs-gap 0 ) false 1 0 1522963006678 The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. Observations consist of a set of exposures that just avoid saturation on the target star using a 1k sub-array and then a longer exposure set with a spatial scan to get nearby fainter field stars. All observations should be done within a single visiblility window. The scheduling window is based on needing to get advance information for the occultation prediction while being close in time to the occultation. These observations should be done in mid-May, preferably somewhat before visit 09 of HST-GO-15158. 1525049745000 262.7596669662006 (Tic-Visit :proposal-id 15450 :visit-id "15" :proposal-version -1 :trans-version "20171009" :date "05-Apr-2018 15:16:46.0" :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 1226288 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15450 :visit-id "15" :obset-id "15" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15450 :visit-id "15" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2780 :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 3217 :pcs-gap 0 ) true 1 0 Similar observations with HST-GO-14926 used BLADE=A but this was flagged as an error with APT. This is being done as a spatial scan to increase the dynamic range of the images. The rate is chosen to be 1.5 pixels per 16 seconds. 16 seconds is the time for the target star to reach ~80% of saturation. The exposure time is set to put four full-frame exposures in the visibility window with a little bit left over to make sure this will schedule anywhere in the entire scheduling window requested. The angles are all different to mitigate against systematic field star overlap.