Proposal Details - 0720018
Continuation of 06K0003: Confirming the Asymmetry of the Positron Annihilation Radiation from the Inner Galactic Disk (Weidenspointner)

Proposal Abstract

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.

Observation Strategy (Recommended by TAC)

Total of 2 Ms in the standard 5x5 dithering mode on two separate regions centred on (l, b) = (25, 0) and (-25, 0), respectively. Each pointing lasts 2000 seconds, and so each 5x5 raster takes about 12.5 hours. Observations of the two regions will be alternated in order to observe each one twice in a single revolution. This strategy is designed to minimise systematic uncertainties arising from background variations, and determine the difference in the flux between the two fields in a robust and largely model-independent way.

Proposal grade: A

Data Rights (Recommended by TAC)

The TAC has allocated the following specific data rights to this proposal: positron/electron annihilation line (511 keV) and ortho-positronium continuum emission.

Exposure Map

The exposure maps are in galactic coordinates and units of ksec, and the colour scale is indicated at the bottom. The green lines provide the 100 ksec contour.