Discovered on January 27, 2020, by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey at Mauna Loa Observatory, 2020 BX12 has an absolute magnitude of 20.6 and an Earth minimum orbit intersection distance (MOID) of 0.0019 au (0.75 lunar distances), making it a potentially hazardous asteroid (PHA). It passed 0.0292 au (11.3 lunar distances) from Earth on February 3, 2020. The next comparably close approach of 2020 BX12 is predicted for January 31, 2101, at a distance of 0.045 au.

S-band radar observations from the Arecibo Observatory planetary radar system on February 4 and 5, 2020, identified 2020 BX12 as a binary system. Delay-Doppler images revealed a primary diameter of 270 ± 90 meters and a secondary diameter of 70 ± 30 meters. The primary's rotation period of 2.5 ± 1 hours is near the spin barrier for objects >200 meters in diameter, while the secondary's period of 25 ± 5 hours suggests tidal locking.

We acquired spectral data (0.48-0.92 microns) using the OSIRIS instrument on the Gran Telescopio Canarias (10.4 m) on February 15, 2024. The spectral analysis suggests a Bus-DeMeo taxonomic class of Sr or Q. Using the Drucker-Prager cohesion criterion, we estimate a cohesion of a few hundred pascals, which is consistent with the nearly strengthless rubble pile structure expected for a binary asteroid.

Subsequent shape modeling with the SHAPE software, which varies shape and spin parameters to find a model that minimizes the objective function (weighted sum of squared residuals between model and data, plus penalties for physically implausible models), yields three-dimensional models of both components.

In this study, we present results derived from the shape models which facilitate the calculation of mass and density. We analyze radar and spectroscopic constraints on the system components, addressing taxonomic classification, rotational and orbital periods, density, and cohesion. The implications of these findings are discussed in the context of enhancing our understanding of the physical properties of this binary PHA.