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    Re: Visual satellite position fix
    From: Peter Monta
    Date: 2013 Aug 12, 18:53 -0700

    Yes, I think there were several satellite optical triangulation
    projects in the mid-1960s.  They used the large passive Mylar-balloon
    satellites (Echo and friends).  There's a really entertaining film
    describing the teams and equipment that went to northern Canada to
    test the technology---this would have been around 1963 or 1964---with
    their large, ~20 cm cameras (using silver-halide film of course),
    paper-tape sequencers, quartz clocks.  It apparently developed into a
    near-worldwide system of a few dozen baselines, just before Doppler
    satellites took over.
    
    It's interesting to think of ways these projects could be replicated
    with modern, low-cost equipment.  I'd like to get back to playing with
    photographic techniques.  What can be done with handheld
    point-and-shoot cameras, especially the recent high-zoom
    image-stabilized types?  A lot, I suspect.
    
    Crazy idea:  it would be a good joke to use GPS in optical mode.
    Frank mentions ISS, and of course that's great for detection and
    photography, since it's so incredibly bright.  But he rightly points
    out that since it's an LEO object, the orbital prediction degrades
    beyond a few weeks.  Maybe there's some fun to be had in considering
    dimmer objects that are in higher orbits and are thus more
    predictable, far away from atmospheric drag and Earth's lumpy gravity
    field.  The extreme example would be GPS.  The orbits are very well
    characterized (~few cm), and if they don't maneuver very often, the
    orbital predictions should last a long time.  Same goes for the
    geodetic satellites (no risk of maneuvering there) or geosynchronous
    communications satellites.
    
    The downside is that all of these are dim, visual magnitude at best
    around 12.  But with a modest telescope they could certainly be imaged
    against the background star field, and then it's just triangulation.
    GPS satellite shots are really just lunars, but 20 times better.
    
    If brighter objects are wanted for use aboard ship, where motion might
    limit exposures to 1/100 second or so, how about the Cosmos rocket
    bodies?  Those are magnitude 3.5 or so, and they don't maneuver.
    There are a lot of them, so availability should be pretty good.
    They're in LEO, though.
    
    Cheers,
    Peter
    
    ps: speaking of geodetic satellites:  a satellite-laser-ranging
    station on ship?  Fire the laser at the top of the swell?  I know,
    totally, *totally* impractical.  Probably.  :-)
    

       
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