 Hygiea is an unusually slow rotator, taking 27 hours and 37 minutes for a revolution, whereas 6 to 12 hours are more typical for large asteroids. Its direction of rotation is not certain at present, due to a twofold ambiguity in lightcurve data that is exacerbated by its long rotation period — which makes single-night telescope observations span at best only a fraction of a full rotation — but it is believed to be retrograde. Lightcurve analysis indicates that Hygiea's pole points towards either ecliptic coordinates (β, λ) = (30 °, 115 °) or (30 °, 300 °) with a 10°uncertainty. This gives an axial tilt of about 60°in both cases.
