Abstract:
High speed optical photometric observations of the hard X-ray source EX Hya, carried out with the reflector of the Kevalur Observatory, are presented. The observations with time resolutions of 1 s or 2 s were made on four nights in March 1982 for a total duration of 6.8 h. Light curves that reveal fast flickerings and the 67 min oscillations are presented. A new ephemeris for the photometric period confirms the trend towards decreasing period on a time scale of 10-million years. Evidence for the presence of interpulses in the light curves between successive photometric maxima