Perseus and Coma clusters of galaxies at energies above 20 keV

Observations of the Perseus and Coma clusters of galaxies were made on June 21, 1974, with a balloon-borne X-ray telescope (energies approximately 20--150 keV). No positive detection was made. Data favor a thermal bremsstrahlung mechanism for the X-ray production in the Perseus cluster of galaxies over the inverse Compton mechanism. In the case of the Coma cluster of galaxies, data are inconclusive with respect to determining the origin of the X-rays