Published online by Cambridge University Press: 14 August 2015
Observations of 3–12 keV X-ray emission from NGC 5128 (Cen A) were made by Vela spacecraft over the period 1969–1979. These data are in good agreement with previously reported data, but are much more complete. Numerous peaks of X-ray intensity occurred during the period 1973–1975, characterized by rapid increases and equally rapid decreases (in less than 10 days). Thus it seems probable that most of the X-ray flux from the nucleus of Cen A came from a single source of small size.