Identifying galaxies within 1 MPc

Erik Max Francis wrote:
> One issue we haven't mentioned is despite being good beacons, pulsars
> aren't perfect. Far enough away, even though in the Galaxy, and they'd
> be hard to detect, so if you were far enough from our solar
> neighborhood, even you were in the (feeble at that distance) beam of
> those reference pulsars you might not be able to detect it.

What's a good maximum range for a pulsar beam? Hundreds of light-years?
Thousands? Tens of thousands? Etc.

Yousuf Khan

In article <FICdnQgQVqdX-gDYnZ2dnUVZ_uOmnZ2d DeleteThis @speakeasy.net>,
Erik Max Francis <max DeleteThis @alcyone.com> writes:
> From skimming papers on pulsar distances on Google, it looks like the
> effective range is ~6 kpc, or perhaps ~2 kly.

Dropped a decimal there: 6 kpc \approx 20000 LY. I agree with the
number, which is of course based on present Earth technology.

I think the point of the Pioneer and Voyager plaques was that any
advanced Galactic civilization would have a comprehensive map of
pulsars throughout the Galaxy and know their behavior over long spans
of time. _Given that information_, the probe's origin could be
located both in space and time.

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Steve Willner Phone 617-495-7123 swillner DeleteThis @cfa.harvard.edu
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