Named in honor of Wilbur N. Christiansen (1913– ), foreign member of the Chinese Academy of Sciences and unfailing friend of Chinese astronomers. A pioneer in radio astronomy, he invented and developed a series of radio telescopes that in their time provided the highest angular resolution. These were the “grating telescope”, the “grating cross” and the “rotational synthesis telescope”. His textbook on radio telescopes, with Högbom, was translated into Russian and Chinese. Immediately after the discovery of the 21-cm hydrogen line in space, he confirmed this and went on to make the first map that showed we live in a spiral galaxy. He served as a vice president of the IAU and as president of URSI, and he now is an honorary president of URSI. (M 33388) _ _.