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    From: Frank Reed
    Date: 2008 Sep 22, 21:44 -0400

    First, credit to Paul S. for inventing the clever name "iKamal". Very funny!
    But alas, if we market one, I can almost guarantee that Apple would claim
    trademark infringement. They'll probably go after "iAm" one of these days...
    I was thinking while driving cross-country yesterday about some ways to make
    a sort of cheap (well, at least not crazy expensive) navigational system
    using off-the-shelf digital levels or other tricks. Imagine creating a
    specialty device based on a moderately high-end digital camera ($1000 range)
    with a built-in digital level and the computing capabilities of an average
    modern cell phone with a built-in almanac of all objects down to sixth
    magnitude valid for some period of time. You snap a photo or two at night.
    With the right settings, you have dozens and dozens of stars in every image.
    Using standard astrometric algorithms, the device calculates with great
    accuracy the spot in the heavens it's centered on. A digital camera today
    can achieve 0.1' accuracy when properly calibrated with relatively little
    calculational sophistication. Now if we could get the vertical (or level)
    accurate to some comparable level, we would quickly have a nice navigation
    system capable of continuous position display, and impressive accuracy,
    whenever the sky is clear. Using inertial sensors, we could get a good
    measure of the vertical. But how good? And at what price? And would such a
    technologically complex system be competitive when GPS is available? Another
    approach to get a level would be to take photos pointing towards low
    altitudes (five to ten degrees). With dozens of stars in each image all
    contributing to a statistical solution, you could get a very good estimate
    of the position of the horizon by looking at the apparent refractions in the
    stars' positions (I think it would help to have two cameras in this case,
    pointing towards roughly perpendicular azimuths). Note that the camera does
    not need to be aimed at anything in particular. Any old patch of sky would
    Just some things that iPonder...
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