Named in honor of Albert Georg Sijthoff, publisher, owner of the former Zeiss planetarium in The Hague and first president of the board of the Omniversum space theater there. Through his lifelong efforts he greatly contributed to the popularization of astronomy in the Netherlands. He played a key role in founding Omniversum, the main center in the Netherlands for the popularization of science in general and astronomy in particular. (M 12458) _ _.