0720018

ABRIDGED: We propose to continue on observational program dedicated to confirming a distinct and unexpected asymmetry in the 511 keV line emission emanating from the inner Galactic disk that was reported by Weidenspointner et al. 2008. For AO-6 a first fraction of the required 4.1 Ms of observation time has already been granted here we request the time that remains unobserved after AO-6 (about 2.4 Ms) to complete the proposed program. [truncated! Please see actual data for full text]