187000

187000 (1999 XY12) is a minor planet of the inner main asteroid belt. It was discovered on 23 September 1999 by the Lincoln Near-Earth Asteroid Research (LINEAR) survey at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico. The asteroid received its provisional designation 1999 XY12 before being assigned the permanent number 187000 by the Minor Planet Center on 12 January 2001.

The orbit of 187000 lies entirely within the main belt, between the orbits of Mars and Jupiter. It has a semi‑major axis of approximately 2.48 astronomical units, an eccentricity of 0.185, and an inclination of 5.3° relative to the ecliptic. Its orbital period is about 3.90 years (1,425 days). The body does not belong to any recognized asteroid family.

Photometric observations have indicated a rotation period near 2.9 hours, suggesting a relatively fast-spinning object. The estimated diameter, based on its absolute magnitude of 15.3 and an assumed albedo of 0.15, is roughly 5.6 kilometres. No extensive spectral data are available, so its composition is not firmly classified but it is likely to be stony (S‑type) like many asteroids in this region.

No private or official name has been assigned to the asteroid; it remains officially known only by its numerical designation. The Minor Planet Center records no mention of a special designation or naming proposal, and the asteroid has not been cited in any major survey publications beyond its discovery and orbital determination.