Observations of the Lunar Occultation of Abell 401 with HEAO-1 A-1. Ulmer, M. P. ; Cruddace, R. G. ; Kinzer, R. L. ; Wood, K. S. ; Evans, W. D. ; Byram, E. T. Abstract Publication: Bulletin of the American Astronomical Society Pub Date: June 1978 Bibcode: 1978BAAS...10..500U