Overview
- Astronomer Matthew Holman flagged the object in Rubin Observatory data on 13 October after running a specialized moving‑object search on repeated southern‑sky images.
- Rubin recorded the object 30 times over 20 nights between March and July 2026, and the team recovered additional archival detections that extend back to 2016 to fix its orbit.
- The Minor Planet Center published the discovery under provisional designation 2026 ED138 on 27 October, listing an orbit at roughly 46 astronomical units and an inclination of about 25 degrees.
- Brightness and distance give a wide diameter range of about 600–1,500 km, which would place ED138 among the largest known trans‑Neptunian objects but leaves dwarf‑planet status unconfirmed.
- Confirming whether ED138 is a dwarf planet requires infrared observations and direct constraints on its shape, and the find highlights Rubin’s ability to reveal large, previously missed bodies in dense star fields.