(523764) 2014 WC510

Lore & Background

2014 WC510 was first observed by the Pan-STARRS 1 telescope on 8 September 2011 but was not recognized as a new object until 20 November 2014. The Minor Planet Center announced it on 17 July 2016 and assigned permanent number 523764 on 25 September 2018. Its orbit is elongated (eccentricity 0.25) and inclined 19.5 degrees to the ecliptic, with perihelion at 29.5 AU and aphelion at 48.9 AU. It last passed aphelion in the early 20th century and is approaching perihelion by 2032.

On 1 December 2018, 2014 WC510 occulted a 15th-magnitude double star, observed by astronomers and citizen scientists across the West Coast of the United States and Canada as part of the RECON project. Six of 41 sites reported dimming; five detected two consecutive dimmings due to the star's double nature. One site in Bishop, California, detected a separate shorter dimming, later identified as an occultation by a secondary component. The projected separation during occultation was 349 ± 29 km, but Hubble Space Telescope imaging on 6 March 2024 revealed a separation of at least 2,600 km, indicating the system was near an edge-on configuration.

The primary and secondary components have diameters of 181 ± 16 km and 138 ± 32 km, respectively, with the secondary about 75% as large as the primary. Their combined absolute magnitude of 7.2 and estimated albedo of about 5% make 2014 WC510 one of the darkest objects measured with stellar occultations, darker than Arrokoth.

Reader's Guide

The discovery of 2014 WC510's binary nature through stellar occultation highlights the power of citizen science and coordinated observation campaigns like RECON. Prior to the occultation, the object had only a 3-year observation arc with significant orbital uncertainty; precovery searches and follow-up Pan-STARRS observations extended the arc to 6.3 years, and highly accurate astrometry allowed a reliable occultation prediction. The large change in projected separation between the 2018 occultation and 2024 Hubble observations suggests the system was nearly edge-on, possibly with mutual transits or occultations. As a small plutino, 2014 WC510 belongs to a population of trans-Neptunian objects thought to have a primordial origin similar to Arrokoth. Its measured diameters and dark surface provide rare direct size and albedo data for small TNOs, though the system's mass and density remain unknown due to undetermined orbital parameters.

Did You Know?

• 2014 WC510 was first observed on 8 September 2011 but not recognized as a new object until 20 November 2014.
• Its binary nature was discovered when its two components occulted a star on 1 December 2018, observed by the RECON citizen science project.
• The primary and secondary components have diameters of about 181 km and 138 km, respectively.
• Hubble Space Telescope imaging in March 2024 showed the components are separated by at least 2,600 km.