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    Re: Just getting started
    From: Alexandre Eremenko
    Date: 2007 Jan 18, 10:06 -0500

    
    On Thu, 18 Jan 2007, Fred Hebard wrote:
    
    > Gary,
    >
    > I believe objects for adjusting the index
    > correction have to be
    > several miles away before parallax is insignificant.
    
    One mile minimum, two miles are more than enough.
    
    > The lake may also not be large enough
    > to give a nice horizon (several
    > miles).
    
    It is nice if you do not see the other shore.
    
    > There is a dip short table
    > in Bowditch to accommodate this
    > problem.
    
    Dip is irrelevant for IC checking using the horizon.
    All you need for IC checking is a remote
    (at least 1 mile away) straight line.
    An electric wire will do the same if you are able to see an
    electric wire 1 mile distant.
    
    There is actually some disagreement, what is the best
    object to check the IC.
    Some recommend a star, some recommend the horizon,
    and Frank Reed recommends the Moon.
    
    My own experience shows that Sun is the best,
    a VERY SHARP horizon probably goes second.
    
    Alex.
    
    
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