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Occultation Observation Support for New Horizons KBO Encounter

Having completed its successful flyby of the Pluto system, the New Horizons spacecraft is on a trajectory for a January 2019 encounter with the 2014 MU69, an approximately 40 km diameter member of the cold classical Kuiper Belt. Earth-based observers have an opportunity to probe the Hill sphere of MU69 and potentially constrain its position and diameter through upcoming stellar occultation events. Three events are forecast in 2017: June 3, July 10, and July 17. Each event is depicted in detail below. These figures are the best available solution as of 2016 December 11 and are provided by Eliot Young with credit to Marc Buie, Larry Wasserman, and Simon Porter. Ongoing updates will be available at

For ground-based observers, particular focus is being directed toward the 2017 June 3 event, for two reasons:
- It crosses two continents (Africa and South America) at locations that have reasonable prospects in terms of setting up a picket fence of observers.
- A detection by ground-based observers on 2017 June 3 will greatly refine the position, thereby greatly improving the chances of SOFIA getting in the shadow path on for the 2017 July 10 and July 17 events.

Interested observers willing to conduct and coordinate their measurements should contact

(Click figure to get full-resolution PDF image)


NH -08194514G by 14MU69 Gaia *, MWB-H-PM
2017/06/03 03:11:50
RA: 19 03 34.493 DEC: -20 34 39.34
Diam: 75.0 = 0.002as Max Duration: 3.7s Q: 82.1 Solar elongation: 147.6
Lunar elongation: 103.3 Illuminated: 66.3%
Sun altitude at -12.0 shown dotted
Ticks from: 03:07:00 to 03:17:00 every 1 min




NH -07659414G by 14MU69 Gaia * MWB-H-PM
2017/07/10 07:45:52
RA: 19 00 41.620 DEC: -20 38 44.53
Diam: 75.0 = 0.002as Max Duration: 3.1s Q: 81.8 Solar elongation: 175.7
Lunar elongation: 16.7 Illuminated: 98.7% Sun altitude at -12.0 shown dotted
Ticks from: 07:42:00 to 07:50:00 every 30 sec




NH -07544526G by 14MU69 Gaia * MWB-H-PM
2017/07/17 03:49:50
RA: 19 00 08.292 DEC: -20 39 37.97
Diam: 75.0 = 0.002as Max Duration: 3.1s Q: 81.8 Solar elongation: 169.3
Lunar elongation: 105.1 Illuminated: 46.2%
Sun altitude at -12.0 shown dotted
Ticks from: 03:46:00 to 03:53:30 every 30 sec


Exploration Missions to the Kuiper Belt And Oort Cloud

With the 2015 flyby of Pluto and the planned 2019 flyby of KBO 2014 MU69, the New Horizons mission has only undertaken the very earliest reconnaissance phase of the exploration of the Kuiper Belt.

The overall science strategy for incrementing knowledge of solar system objects was articulated by the Committee on Planetary and Lunar Exploration (COMPLEX) in the 1970's; it begins with flyby reconnaissance and progresses exploration with orbiters and then landers.

The Kuiper Belt and Oort Cloud will next require a series of flyby missions to explore the diversity of phenomenology and origins of the objects found in these vast, primordial reservoirs. Additionally, Pluto system orbiters or landers are also needed to understand its unexpectedly complex surface geology, atmospheric dynamics and volatile transport, its satellite system, and the possibility and characteristics of its suspected interior ocean.

Anyone interested in potentially joining a Pluto follow-on mission interest group should contact Alan Stern at

There were 19 new TNO discoveries announced since the previous issue of Distant EKOs:

2013 VJ24, 2014 SB350, 2014 SE350, 2014 SF350, 2014 SH350, 2014 SJ350, 2014 SL350, 2014 SM350, 2014 SN350, 2014 ST349, 2014 SX349, 2014 TE86, 2014 UB225, 2014 UC225, 2014 XY40 2014 XZ40, 2015 DB225, 2015 DC225, 2016 BP81

and 12 new Centaur/SDO discoveries:

2012 FN84, 2014 SC350, 2014 SG350, 2014 SK350, 2014 SO350, 2014 UA225, 2014 UZ224, 2014 YL50, 2015 DA225, 2015 FW392, 2015 UK84, 2015 VT152

Reclassified objects:

2014 YY49 (SDO Centaur)
2015 FW392 (SDO TNO)

Objects recently assigned numbers:

2004 VN112 = (474640)
2014 QB442 = (480017)

Current number of TNOs: 1789 (including Pluto)
Current number of Centaurs/SDOs: 689
Current number of Neptune Trojans: 17

Out of a total of 2495 objects:
   713 have measurements from only one opposition
     676 of those have had no measurements for more than a year
       311 of those have arcs shorter than 10 days
(for more details, see: