Debris search around (486958) 2014 MU69: Results from SOFIA and ground-based occultation campaigns

The New Horizons spacecraft is scheduled to fly by the cold classical KBO 2014 MU69 on 1-Jan-2019. The spacecraft speed relative to the MU69 will be in excess of 14 km/s. At these encounter velocities, impact with debris could be fatal to the spacecraft. We report on searches for debris in the neighborhood of MU69 conducted from SOFIA and ground-based sites. SOFIA observed the star field around MU69 on 10-Jul-2017 (UT) with their Focal Plane Imager (FPI+), operating at 20 Hz from 7:25 to 8:10 UT, spanning the time of the predicted occultation. Several large fixed telescopes observed the 3-Jun-2017, 10-Jul-2017 and/or the 17-Jul-2017 occultation events, including the 4-meter SOAR telescope, the 8-meter Gemini South telescope, and many 16-inch portable telescopes that were arranged in picket fences in South Africa and Argentina. We report on the light curves from these observing platforms and constraints on the optical depth due to debris or rings within the approximate Hill sphere (about 60,000 km across) of MU69. This work was supported by the New Horizons mission and NASA, with astrometric support from the Gaia mission and logistical support from Argentina and the US embassies in Buenos Aires and CapeTown. At SOAR, data acquisition has been done with a Raptor camera (visitor instrument) funded by the Observatorio Nacional/MCTIC.