Proposal Details - 0820024
Determining the longitude distribution of the asymmetric positron annihilation radiation from the inner Galaxy (Weidenspointner)

Proposal Summary (based on proposal abstract)

Building on successful AO-6 and AO-7 observations, a similar observational program is proposed, dedicated to determining the longitude profile of the asymmetric positron annihilation line radiation from the inner Galaxy first reported by Weidenspointner et al. (2008). Crucial measurements to achieve this goal can be made by applying the successful chopping pointing strategy to fields at (l, b)= (+/-14 deg, 0 deg), that cover both the inner disk as well as the outer bulge region, for a total of 2.5 Ms.

Observation Strategy (Recommended by TAC)

Total of 2.5 Ms in the standard 5x5 dithering mode on two separate regions centered on RA, Dec = 273.970, -16.783 (l, b = 14, 0) and RA, Dec = 256.855, -40.555 (l, b = -14, 0), 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. The observations at l = -14 are amalgamated with part of the observations of RX J1713.7-3946 (proposal 0820027), for a total of 1.25 Ms

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

Exposure maps are in units of s and shown using Galactic coordinates. The intensity scale is given by the colourbar, and there are contour levels at 100, 300 and 500 ks.