The intensity of the new microwave radiation observed by Shivanandan, Houck, and Harwit is adequate to produce, by Compton scattering on cosmic-ray electrons, the flux and distribution of ∼100-MeV $\gamma$ rays reported by Clark, Garmire, and Kraushaar.

• Received 17 December 1969

DOI:https://doi.org/10.1103/PhysRevLett.22.550