The Very Long Sidereal Period of 1807 Slovakia

A long synodic rotation period of about 308 h was found for asteroid 1807 Slovakia in its 2008/2009 apparition based on a combination of data from Modra and the Minor Planet Center (MPC). Asteroid brightness estimates found in the MPC data covering several previous apparitions not only confirmed the synodic period and large amplitude of the lightcurve of ~1.0 mag, but also led to absolute magnitude (H) and sidereal period determinations, those being H = 12.6 ± 0.1 and Psidereal = 311.75 ± 0.09 h. The sense of rotation is retrograde.