(523731) 2014 OK394 (provisional designation1995 SN55) is a trans-Neptunian object that orbits in the outer Solar System beyond the orbit of Neptune. First observed as 1995 SN55bySpacewatch on 20 September 1995, it was a lost minor planet with an insufficiently defined orbit with only 36 days of observations.[9] On 8 October 2010, it was rediscovered by the Pan-STARRS 1 survey and later announced as 2014 OK394 in July 2016.[1] It was not until November 2020 when amateur astronomers S. Deen and K. Ly identified 2014 OK394 and 1995 SN55 as the same object.[10] This identification was confirmed and announced by the Minor Planet Center in January 2021.[11]
Once thought to be a centaur crossing the orbits of the gas giants,[9]1995 SN55 is now known to be a trans-Neptunian object in a 3:5 orbital resonance with Neptune.[4] With an estimated diameter between 160–280 kilometers (99–170 miles), it was formerly considered one of the largest centaurs.[7][12][13]
1995 SN55 was near perihelion 35.4 AU from the Sun when it was first observed in 1995, by astronomers Nichole Danzl and Arianna Gleason of the Spacewatch survey at Kitt Peak Observatory in Arizona, United States.[5] It was only observed 14 times over 36 days, from 20 September to 26 October 1995.[9] The discovery observations of 1995 SN55 were published and announced by the Minor Planet Center on 11 June 1999.[5] By 2020 the 3-sigma uncertainty in the heliocentric distance to the original orbit solution for 1995 SN55 was approximately ±20 AU (3.0 billion km).[citation needed]
On 30 November 2020, amateur astronomers S. Deen and K. Ly identified 1995 SN55 as the 3:5 resonant trans-Neptunian object (523731) 2014 OK394, which was discovered by Pan-STARRS 1 in 2010.[10] The identification was published by the Minor Planet Center on 27 January 2021.[11]
2014 OK394 orbits the Sun at an average distance of 42.33 AU once every 275 years. Its orbit has an eccentricity of 0.16 and an inclination of 4° with respect to the ecliptic plane. Over the course of its orbit, its distance from the Sun ranges from 35.4 AU at perihelion to 49.3 AU at aphelion. 2014 OK394 is in a 3:5 mean-motion orbital resonance with Neptune; for every three orbits it makes, Neptune orbits five times.[3] Its orbit has a minimum orbit intersection distance approximately 5.6 AU (840 million km; 520 million mi) from Neptune's orbital path.[4]
