OSSE/SMM/TGRS observations of positron annihilation radiation

Extensive observations using the CGRO/OSSE instrument have permitted the first investigations of the distribution of both line and continuum positronium emission in the Galaxy. Maps have been generated of both components of the total annihilation radiation. In addition, potential bulge and disk distributions have been tested against the measurements of each component. At the level of this study, the two emissions appear to follow a similar distribution for both bulge and disk components. Differences between these maps would be suggestive of a variation of the positronium fraction, which is a diagnostic of the characteristics of the annihilation media. The previously reported enhancement of 511 keV emission from positive latitudes is not present at a significant level in the positronium continuum maps. We conclude this discussion with an assessment of the ability of the SPI and IBIS instruments to resolve ambiguities from the OSSE/SMM/TGRS studies.