Recent results of SMM on the galactic 511 keV annihilation radiation exhibit a constant flux during 4–5 years, in total disagreement with post 1980 balloon observations. However, all these results are compatible if one admits the existence of a variable point source near the Galactic Center of FP ∼ 10−3 ph cm−1 s−1 and a diffuse interstellar source of positrons: FD ∼ 1.5−1.8 10 ph cm−2 s−1 rad−1. Evaluations of 26Al and 56Co decays contributions have been given last year (2) and that of 44Ti decays more recently (3). We have studied the nature of the sources of the main e+ − emitting radioisotopes − SN and novae − and their galactic distributions using the observational data at 511 keV and at 1809 keV, the galactic angular distributions considered by Leising and Clayton (4) and the nucleosynthesis of the models of novae and SN of Woosley and his collaborators (5).