title: Optical pulse of a periodic radio star.
abstract: The pulsating radio star reported by Hewish et al. (1) has been studied in the blue region of the optical spectrum and found to have a pulse amplitude less than 10 percent of the photon count expected for 18th magnitude. No upper limit to a sinusoidal oscillation less than or equal to a complete modulation can be set.
authors.forename: J G
authors.initials: JG
authors.lastname: Duthie
authors.forename: C
authors.initials: C
authors.lastname: Sturch
authors.forename: E M
authors.initials: EM
authors.lastname: Hafner