Orbits and Occultation Opportunities of 15 TNOs Observed by New Horizons

Abstract

Abstract We present high-precision orbits for 15 trans-Neptunian objects (TNOs) that have been observed by NASA’s New Horizons spacecraft at distances from 0.092 to 2.2 au. We also give predictions of 66 future opportunities to observe stellar occultations by them in late 2021–2029, eight of which are possible to observe from the United States. Observation of these stellar occultations would allow searches for more contact-binary TNOs like the New Horizons flyby target (486958) Arrokoth. In addition, measuring the sizes and albedos of more TNOs helps to better calibrate models of the size–frequency distribution of the broader Kuiper Belt. The 15 TNOs we investigate are unique in that they have been observed by the New Horizons spacecraft, providing high-parallax observations that greatly help to restrict the uncertainty of their orbits. Our orbit determinations combine detailed analyses of observations from the Magellan, Subaru, and CTIO ground-based observatories; the Hubble Space Telescope; and the New Horizons spacecraft. They are referenced to the Gaia DR2 star catalog, while the occultation predictions use the latest Gaia EDR3 catalog for the occultation stars. Our analysis allows us to understand the uncertainties for all of our predicted occultation opportunities and thus the need for additional astrometry, if any, to observe these events and measure the sizes and shapes of small–midsize TNOs.