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    Re: Bubble Sextant
    From: Steven Grobler
    Date: 2003 Feb 13, 21:59 +0800

    Hi  Jim
    
    Thanks for your comments and kind words.
    
    I still need to put some more time into my star sights - I seem to be
    getting better result from sun sights. This may be because one of my
    lamps is not working, so I struggle to get the time noted quickly.
    Also, the mosquitos are a bit distracting!
    
    In terms of the Delta between my actual position and the lines of
    position, I usually get sun sights with Delta's of between -3NM  and
    +3NM. They are not well separated in azimuth terms and the fix is about
    5 NM from the > actual position.
    
    I'd be interested in seeing any photos of your instrument you may have.
    
    Regards
    Steve G
    
    > ----- Original Message -----
    > From: "Jim Dullea" 
    > To: 
    > Sent: Tuesday, February 11, 2003 9:05 PM
    > Subject: Re: Bubble Sextant
    >
    >
    > > Steve,
    > >
    > > Very nice site with great pictures.  Your learning curve on position
    > > accuracy seems at least comparable to mine using the Bendix Navy Mk
    V with
    > > about the same level of practice.  I agree with you assessment that
    in
    > > aircraft at several hundred Knots this accuracy is probably
    > sufficient....I
    > > don't expect to get much better than the 2-3 nm
    > >
    > > Since I know my AP using GPS very accurately and not needing to use
    a
    > moving
    > > fix I used multiple sites throughout the day trying out stars,
    planets,
    > moon
    > > and sun.  I achieved the following
    > >
    > > Day 1:  Sun lower limb, Rigel, Betelgeuse ---   4.45 nm
    > > Day 2:  Sun lower limb, moon lower limb, Rigel  3.86 nm
    > > Day 3:  Sun and moon lower limb and Polaris     4.91 nm
    > > Day 4:  Sun and moon lower limb and Jupiter     8.61 nm (poorly
    dispersed
    > in
    > > azimuth for a good position, all within 90 degrees)
    > >
    > > Use all 12 LOP's  2.84 nm
    > >
    > > From the plot it appears I have better plots using stars and planet
    than
    > > with the moon and sun which makes me want to consider how
    > >
    > > Jim Dullea
    > >
    
    
    

       
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