The Crab Nebula pulsar, NP 0532, is the only one of the 56 known pulsars which has been observed to pulse in the optical spectrum. Even more spectacular are the vast quantities of pulsed X-rays which it has been found to emit. Soft X-rays in the 1–10 keV region have been observed during four sounding rocket flights (Fritz et al., 1969; Bradt et al., 1969; Boldt et al., 1969; Ducros et al. 1970) and harder X-rays, 25–200 keV, have been detected during two balloon flights (Fishman et al., 1969a,

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... ; Floyd et al., 1969). From the results of these six experiments we summarize the properties of the X-ray pulsations from NP 0532.