Barnard's Star
Peter van de Kamp, Wulff's predecessor at Swarthmore, made claims since the 1960s of a planetary system around Barnard's Star. After van de Kamp's retirement in 1972, the photographic plates made using the Sproul refractor telescope were shown to be flawed, affecting Van de Kamp's Barnard's Star claim as well as claims of planetary systems around other near-by stars made at the same time by staff astronomer Sarah Lippincott. Upon his assumption of directorship in 1973, Wulff began questioning the findings of his former colleague and began publishing criticisms from 1976 onwards; Van de Kamp never admitted any error and the two friends are reported to have become estranged over this affair.