Proposal Details - 0920013
Continuation of 0820024 - Determining the longitude distribution of the asymmetric e+ radiation from the inner galaxy. (Weidenspointner)

Proposal Abstract

The proposal 0820024, to examine the longitude distribution of the 511 keV positron annihilation emission from the inner galaxy, was accepted but awarded only half of the time estimated as necessary. It was encouraged to resubmit in AO9 to achieve the required exposure. Results to date are encouraging and a further 2.5 Ms of observations have been requested employing the successful chopping pointing strategy to observe alternately fields at (l, b)= (+/-15 deg, 0 deg), that cover both the inner disk and the outer bulge region, so providing a total of 5 Ms.

Observation Strategy (Recommended by TAC)

Total of 2.5 Ms in the standard 5x5 dithering mode on two separate regions centered on l, b = 15, 0 (RA, Dec = 274.466, -15.903) and l, b = -15, 0 (RA, Dec = 256.056, -41.352), respectively. Each exposure lasts 1800 seconds; thus each 5x5 grid 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 granted the data rights for 511 keV line and positronium continuum.

Exposure Map

The exposure maps are in galactic coordinates using the Aitoff projection and units of seconds, and the colour scale is indicated at the bottom. The green lines provide the 100, 300 and 500 ksec contour.