2019 BZ3

 is a very small near-Earth asteroid of the Apollo group, approximately 6 m in diameter. It was first observed by the Mount Lemmon Survey on 28 January 2019, just hours after the asteroid's sub-lunar flyby of Earth at less than 0.12 lunar distance.

Orbit and classification
 is an Apollo asteroid, the largest subgroup of near-Earth objects. It orbits the Sun at a distance of 0.96–3.6 AU once every 3 years and 6 months (1,268 days; semi-major axis of 2.29 AU). Its orbit has a high eccentricity of 0.58 and an inclination of 11° with respect to the ecliptic. The body still has a high orbital uncertainty of 5 and 7, respectively. Its observation arc of only 8 days begins with its official first observation at Mount Lemmon Observatory on 28 January 2019.

Close approaches
 has an Earth minimum orbital intersection distance of 0.000457 AU, which corresponds to 0.18 lunar distances (LD). Due to its very small size, however,  is not a potentially hazardous asteroid, which are required to be approximately 140 m in diameter, that is, to be brighter than an absolute magnitude of 22.

On 27 January 2019 at UTC 23:29,  passed Earth at a nominal distance of 48,130 km (0.125 LD)  with a relative velocity of $6 m$. Six hours later, it flew by the Moon at $11.37 km$. The object's next close approaches will occur on 17 December 2025 at a much greater distance of 0.143 AU, and on 29 January 2085 at 0.0142 AU.
 * Flybys

Numbering and naming
This minor planet has not yet been numbered by the Minor Planet Center and remains unnamed.

Physical characteristics
 has an undetermined spectral type. Based on a generic magnitude-to-diameter conversion, the asteroid measures approximately 6 meter in diameter for an assumed albedo of 0.15 and absolute magnitude 28.8. The estimated diameter may vary between 5 and 10 meters depending on whether an albedo for a dark carbonaceous (0.05) or a bright stony (0.25) asteroid is assumed.