A detailed model for positron production by a young pulsar is presented. It is shown that electromagnetic cascades can develop in a young pulsar's magnetosphere, and the model results are applied to the pulsar which is hypothesized to lie near the Galactic center. It is found that such a pulsar would be expected to produce relatively low energy electron-positron pairs with an efficiency rating high enough to explain the observed luminosity of the Galactic center annihilation line. Virtually all of the gamma ray continuum radiation produced in the cascades would be beamed along the magnetic poles of the neutron star, and therefore probably would not be observed from earth. Some observational predictions generated by the proposed model for the Galactic center positron source are given.

High-energy (70 MeV < E < 5 GeV) gamma-ray observations of Cyg X-3 by the ESA satellite COS-B and hard X-ray (14 keV < E < 140 keV) observations by the Leiden-MIT balloon experiment, Leimit, are presented. A comparison with, and a study of earlier results over the 14 decades in energy from 1 keV up to ≡1017eV indicates that the strong variability of Cyg X-3 over more than one order of magnitude at energies below 20 keV does not exhibit itself in the data collected at hard X-ray energies, and the power emitted per decade of energy reaches a minimum in the MeV-GeV region. If the primary gamma-rays up to 1015eV originate close to the central source, absorption by the keV X-rays in the Cyg X-3 binary system could explain the latter phenomenon.