851 Zeissia is an S type asteroid 12.26 Km. in diameter with H = 11.62 and an albeido of .2646. A. W. Harris estimated the period from partial data collected by Wisniewski in 1989 to be 9.9 hours. The data covered about 2/3 of the period.
I conducted three sessions covering the entire period with overlap and determined the period to be 9.34 hours +/- .01h with a magnitude of .42mag. This is a very clean solution and totally consistent with Wisneiwski's data and Harris' analysis in almost every detail. A comparison is included for review.