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Published online by Cambridge University Press: 14 August 2015
This paper reports upon an observation of hard X-radiation from the direction of M87. Earlier (Haymes et al., 1968a), we reported the apparent detection of hard radiation from the general direction of Virgo; the experiment discussed here, conducted 16 months later, recorded approximately the same flux from a smaller region of sky that tends to isolate M87 as the most likely candidate for the source.