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Frank Reed reminds us of an earlier thread "Learn the stars, by phone", that
he started on 13 May this year. I am surprised that he does so. New readers
would be well-advised to follow that thread, to see where it led to.

He writes- "Yes. Augmented reality! This is the cool development in
smartphone technology I was talking about last spring that we could leverage
very easily for celestial navigation education (here's a link to a message
of mine in that earlier thread: http://fer3.com/arc/m2.aspx?i=108258). "

===========================

It turned out that Frank's claims for the precision of such devices, which
relied on the local magnetic field, were based on early statements by
Celestron of the pointing-precision of their "Skyscout" viewer. Frank quoted
a pointing precision of half a degree, which was then challenged as
implausible. And by that time, Celestron's claimed precision had been well
watered-down to 3 degrees, which corresponds to an area of sky which would
contain 36 times as many stars as before. That made a lot of difference. If
you pointed it at Jupiter, it might identify it as Jupiter, but might just
as well identify it as one of several other-bodies, within that
3-degree-radius circle. As it kept many thousands of stars in its
memory-locker, that would be all too likely.

He now invites us to look again at his earlier posting, without drawing
attention to any such defects.

This time, he adds- "The article doesn't mention that this technology
depends not just on location data, but also on orientation data which
generally implies a built-in magnetic compass. There's a way around this in
major cities if you use some sophisticated processing (which can occur
server-side) to take the image, the GPS (or wifi) location data and then
figure out direction based on the buildings seen and maybe even using
shadows if it's daytime. That combined with the simple inertial sensors in
many phones would yield orientation without a magnetic compass."

That notion seems even more implausible than the previous one, for viewers
of the night sky.

He ends his gee-whizzery with - "And now we just need someone to write some
applications that feature the celestial navigation data prominently."

It seems to me, we need someone to invent a way of getting some
pointing-precision first, before we concern ourselves with such
applications. I don't say it's impossible. Maybe, some day, ring-lasers will
be made that can go into a pocket. But not yet; not with sensors that rely
on the local magnetic field.

George.

contact George Huxtable, at  george@hux.me.uk
or at +44 1865 820222 (from UK, 01865 820222)
or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.


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