(678191) 2017 OF69

(678191) 2017 OF₆₉ is a resonant trans-Neptunian object from the Kuiper belt, located in the outermost region of the Solar System in the Kuiper belt's plutino population and measures approximately 533 kilometers (330 miles) in diameter. It was first observed on 26 July 2017, by American astronomers David Tholen, Scott Sheppard, and Chad Trujillo at Mauna Kea Observatories in Hawaii, but not announced until 31 May 2018 due to observations made in April and May 2018 refining its orbit significantly.^[2]

(678191) 2017 OF₆₉

Orbital diagram of 2017 OF69 with other large plutinos: Pluto, Orcus, Achlys (2003 AZ84), and Ixion
Discovery[1][2]
Discovered by	D. J. Tholen S. S. Sheppard[3] C. Trujillo
Discovery site	Mauna Kea Obs.
Discovery date	26 July 2017 (first observed only)
Designations
MPC designation	2017 OF69
Minor planet category	TNO[4] · plutino[5] · distant[1]
Orbital characteristics[4]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 3
Observation arc	6.01 yr (2,195 d)
Aphelion	47.844 AU (7.1574 Tm)
Perihelion	31.418 AU (4.7001 Tm)
Semi-major axis	39.631 AU (5.9287 Tm)
Eccentricity	0.2072
Orbital period (sidereal)	249.49 yr (91,128 d)
Mean anomaly	251.02°
Mean motion	0° 0m 14.4s / day
Inclination	13.654°
Longitude of ascending node	218.53°
Argument of perihelion	215.37°
Physical characteristics
Mean diameter	533 km (est.)[5]
Geometric albedo	0.09 (assumed)[5]
Absolute magnitude (H)	4.6[1][4]

2017 OF₆₉ has not yet been imaged by high-resolution telescopes, so it has no known moons.^[6] The Hubble Space Telescope is planned to image 2017 OF₆₉ in 2026, which should determine if it has significantly sized moons.^[6]

Orbit and classification

2017 OF₆₉ is a large plutino, a subgroup of the resonant trans-Neptunian objects located in the inner region of Kuiper belt. Named after the group's largest member, Pluto, the plutinos have a 2:3 orbital resonance with Neptune.

It orbits the Sun at a distance of 31.4–47.8 AU once every 249 years and 6 months (91,128 days; semi-major axis of 39.63 AU). Its orbit has an eccentricity of 0.21 and an inclination of 14° with respect to the ecliptic.^[4] The body's observation arc begins with a precovery by Pan-STARRS in June 2012.^[1]

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 22 March 2024 (M.P.C. 172722).^[7] As of June 2025^[update], it has not been named.^[1]

Physical characteristics

Diameter and albedo

According to Johnston's Archive, 2017 OF₆₉ measures 533 kilometers in diameter assuming an albedo of 0.09 for the body's surface.^[5] This makes 2017 OF₆₉ a notably large body for how late it has been discovered, being the fifth largest plutino in the Solar System, after Pluto, Orcus, Achlys, and Ixion, and the largest discovered since Orcus in 2004.

Rotation period

As of 2018, no rotational lightcurve of 2017 OF₆₉ has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.^[4]