[3][9] Imaged in January 2018 during a search for the hypothetical Planet Nine,[10] the confirmation of this object was announced in a press release in February 2021 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo.

[5] It requires an observation arc of several years to refine the uncertainties in the approximately 700-year orbital period and determine whether it is currently near or at aphelion (farthest distance from the Sun).

2018 AG37 was first imaged on 15 January 2018 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo when they were surveying the sky using the large 8.2-meter Subaru Telescope at Mauna Kea Observatory, Hawaii, to find distant Solar System objects and the hypothetical Planet Nine, whose existence they proposed in 2014.

[10][13] In two of these images taken one day apart in January, he identified a faint apparent magnitude 25.3 object that moved slowly relative to the background stars and galaxies.

[1] Based on two positions of 2018 AG37 in those images, Sheppard estimated its distance was roughly around 140 astronomical units (AU), farther than 2018 VG18 which was discovered and announced by his team one month earlier in December 2018.

[1] These observations over a two-year period established a tentative orbit solution for 2018 AG37, permitting it to be confirmed and announced by the Minor Planet Center.

[8] Only 2018 AG37's distance and orbital elements that define its position (inclination and longitude of the ascending node) have been adequately determined by its two-year observation arc.

are poorly determined because its observation arc does not provide sufficient coverage of its wide-ranging orbit, especially when it moves slowly due to its large distance.

[2] 2018 AG37's small perihelion distance and elongated orbit implies that it has experienced strong gravitational interactions with Neptune in past close encounters.