Asteroid 532 Herculina - Lightcurves, pole orientation and a model

Photoelectric lightcurves of 532 Herculina in 1984 show two maxima and two minima with a synodic rotation period of 0.39185±0.00002 day (1sigma). During some other oppositions the Herculina lightcurve has only one maximum and one minimum over that same rotation period. The absolute magnitude in V is 6.13±0.02 mag, the phase coefficient in V is 0.037±0.002, and the mean colors are B-V = +0.86±0.04 and U-B = +0.43±0.02. The authors applied photometric astrometry and the results indicate a sidereal period of 0.3918711±0.0000001 day with retrograde rotation for a north pole at 276° long and +1° lat. The uncertainty of the pole is ±1°. A model of Herculina is presented that generates lightcurves consistent with both the observed amplitudes and the timings of extrema over precisely 28,630 sidereal rotations during 30 years.