CCD photometry, spin and shape model of the asteroid 1572 Posnania

Abstract

Lightcurves of the asteroid 1572 Posnania were obtained at six observatories on 19 nights during four apparitions: in 1993, 1994-95, 1996, and 1999. The synodical period is found to be 8.048 hours and the observed amplitudes of brightness variations are in the range of 0.37-0.40 mag. The sense of rotation is retrograde with a sidereal period Psid = 0.3353931 ± 0.0000003 days. The ecliptic coordinates of the pole of this asteroid are λp = 46° ± 6° and βp = -65° ± 5°. The shape of Posnania can be approximated by a triaxial ellipsoid model with semiaxes ratios a/b = 1.35 ± 0.01 and b/c = 1.04 ± 0.03.