Size and Shape Constraints of (486958) Arrokoth from Stellar Occultations

Journal Article · Wed Apr 01 00:00:00 EDT 2020 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AB6CED· OSTI ID:23013142

Buie, Marc W.; Porter, Simon B.; Tamblyn, Peter; Terrell, Dirk; Parker, Alex Harrison; Leiva, Rodrigo; Zangari, Amanda M.; Caspi, Amir ^[1]; Baratoux, David ^[2]; Kaire, Maram ^[3]; Verbiscer, Anne J. ^[4]; Colas, François ^[5]; Diop, Baidy Demba ^[6]; Samaniego, Joseph I. ^[7]; Wasserman, Lawrence H. ^[8]; Benecchi, Susan D. ^[9]; Gwyn, Stephen; Kavelaars, J. J. ^[10]; Ocampo Uría, Adriana C. ^[11]; Rabassa, Jorge ^[12] ; others, and

---

1. Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States)
2. Géosciences Environnement Toulouse, UMR5563 CNRS, IRD and University of Toulouse, 14 Avenue Edouard Belin, F-31400, Toulouse (France)
3. MESRI Allées Papa Gueye Fall Dakar (Senegal)
4. University of Virginia, Department of Astronomy P.O. Box 400325, Charlottesville, VA 22904 (United States)
5. IMCCE, Observatoire de Paris 77 av. Denfert-Rochereau, F-75014, Paris (France)
6. Direction de la Formation et de la Communication DFC/MEN Mermoz pyrotechnie Dakar (Senegal)
7. University of Colorado—Boulder, 2000 Colorado Avenue, Boulder, CO 80309-0390 (United States)
8. Lowell Observatory, 1400 W Mars Hill Road, Flagstaff, AZ 86001 (United States)
9. Planetary Science Institute, 1700 East Fort Lowell, Suite 106, Tucson, AZ 85719 (United States)
10. Herzberg Astronomy and Astrophysics Research Centre, National Research Council of Canada, 5071 West Saanich Road, Victoria BC V9E 2E7 (Canada)
11. NASA HQ, Planetary Science Division, 300 E. Street, SW, Washington DC 20546 (United States)
12. CADIC-CONICET, Bernardo Houssay #200, 9410 Ushuaia, Tierra del Fuego (Argentina)

We present the results from four stellar occultations by (486958) Arrokoth, the flyby target of the New Horizons extended mission. Three of the four efforts led to positive detections of the body, and all constrained the presence of rings and other debris, finding none. Twenty-five mobile stations were deployed for 2017 June 3 and augmented by fixed telescopes. There were no positive detections from this effort. The event on 2017 July 10 was observed by the Stratospheric Observatory for Infrared Astronomy with one very short chord. Twenty-four deployed stations on 2017 July 17 resulted in five chords that clearly showed a complicated shape consistent with a contact binary with rough dimensions of 20 by 30 km for the overall outline. A visible albedo of 10% was derived from these data. Twenty-two systems were deployed for the fourth event on 2018 August 4 and resulted in two chords. The combination of the occultation data and the flyby results provides a significant refinement of the rotation period, now estimated to be 15.9380 ± 0.0005 hr. The occultation data also provided high-precision astrometric constraints on the position of the object that were crucial for supporting the navigation for the New Horizons flyby. This work demonstrates an effective method for obtaining detailed size and shape information and probing for rings and dust on distant Kuiper Belt objects as well as being an important source of positional data that can aid in spacecraft navigation that is particularly useful for small and distant bodies.

• OSTI ID: 23013142
• Journal Information: The Astronomical Journal (Online), Vol. 159, Issue 4; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCURACY
ALBEDO
ASTRONOMY
COSMIC DUST
DETECTION
ECLIPSE
NAVIGATION
STARS
TELESCOPES