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, also known as , is a trans-Neptunian object that orbits in the outer Solar System beyond the orbit of Neptune. First observed as  by Spacewatch on 20 September 1995, it was a lost minor planet with an insufficiently defined orbit with only 36 days of observations. On 8 October 2010, it was rediscovered by the Pan-STARRS 1 survey and later announced as  in July 2016. It was not until November 2020 when amateur astronomers S. Deen and K. Ly identified  and  as the same object. This identification was confirmed and announced by the Minor Planet Center in January 2021. Once thought to be a centaur crossing the orbits of the gas giants,  is now known to be a trans-Neptunian object in a 3:5 orbital resonance with Neptune. With an estimated diameter between , it was formerly considered one of the largest centaurs. Observations

First observation and loss 

 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. It was only observed 14 times over 36 days, from 20 September to 26 October 1995. The discovery observations of  were published and announced by the Minor Planet Center on 11 June 1999. By 2020 the 3-sigma uncertainty in the heliocentric distance to the original orbit solution for  was approximately ±. Recovery 

On 30 November 2020, amateur astronomers S. Deen and K. Ly identified  as the 3:5 resonant trans-Neptunian object , which was discovered by Pan-STARRS 1 in 2010. The identification was published by the Minor Planet Center on 27 January 2021. Classification and orbit 
 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. is in a 3:5 mean-motion orbital resonance with Neptune; for every three orbits it makes, Neptune orbits five times. Its orbit has a minimum orbit intersection distance approximately  from Neptune's orbital path. Numbering and naming 

 was numbered by the Minor Planet Center on 25 September 2018 and received the number  in the minor planet catalog. The alternate provisional designation  was given by the Minor Planet Center on 27 January 2021 after the two objects were linked. , it has not been named. See also 
 Lost minor planet
 1995 GJ – lost trans-Neptunian object
  – misidentified nonexistent minor planet
  – main-belt asteroid originally misidentified as a trans-Neptunian object

References

External links 
 A 300-kilometre space rock has vanished since we saw it in 1995, Joshua Sokol, New Scientist, 25 October 2017
 

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