21873 Jindřichůvhradec

[10] It orbits the Sun in the outer main-belt at a distance of 2.5–3.8 AU once every 5 years and 7 months (2,044 days).

[5] The first precovery was obtained at Crimea–Nauchnij in 1982, extending the asteroid's observation arc by 17 years prior to its discovery.

[9] In September 2010, a photometric lightcurve analysis at the U.S. Palomar Transient Factory, California, gave a long rotation period of 50.5874±0.0664 hours with a brightness variation of 0.61 in magnitude (U=2).

This minor planet was named after Jindřichův Hradec, a south Bohemian town in the Czech Republic.

Founded in the 13th century, it is known for its Renaissance château and Gothic church, which is exactly built on the 15th meridian east of Greenwich.