133 Cyrene is a fairly large and very bright main-belt asteroid that was discovered by J. C. Watson on 16 August 1873 in Ann Arbor, Michigan, and named after Cyrene, a nymph, daughter of king Hypseus and beloved of Apollo in Greek mythology.

It is listed as a member of the Hecuba group of asteroids that orbit near the 2:1 mean-motion resonance with Jupiter.

[8] In the Tholen classification system, it is categorized as a stony SR-type asteroid.

[9] Photometric observations of this asteroid at the Altimira Observatory in 1985 gave a light curve with a period of 12.707 ± 0.015 hours and a brightness variation of 0.22 in magnitude.

This result matches previous measurements reported in 1984 and 2005.