On 4/19/13 11:47 AM, Peter Monta wrote:
Hi Hal,
Why are X-Ray pulsars better than radio pulsars for navigation?
My impression is that it's easier to manage all-sky coverage at x-ray with
a small spacecraft package (I think millisecond pulsars generally emit at
both microwave and x-ray). Also there's some interstellar scintillation at
microwave frequencies, which would hurt short-term timing performance
(something like the ionosphere's effect on terrestrial GNSS).
One of the hits when you google "XNAV detector" is a AAS paper from an
SBIR Phase 1 describing a potential system..
Note that their assumption is that the detector has:
1) 1 square meter detector area
2) Integration time of 100k seconds
3) detector eff 95%
4) detector background rate 0.1ph/s
etc
From what I've heard casually, a detector like this is unobtanium.
http://microcosminc.com/analysis/AAS%2008-054%20XNAV.pdf
For instance, Chandra's detector is a 10x10cm Microchannel Plate,
although the Xray telescope aperture is somewhat larger.
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