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    Re: Longitude at noon
    From: Bruce Cutting
    Date: 2020 Sep 09, 12:21 -0600

    The Davis has tremendous backlash.  ALWAYS come down on the sight from
    the same direction - other than that it is a reasonable instrument - I
    easily make sight within 3 miles.  HAVE FUN
    Quoting Tracy Shrier :
    > Hi Phillip,
    > Monday I took my first marine sextant noon sight off an artificial
    > horizion in my back yard, today I read your post, funny coincidence!
    > Attached is my work up for your interest. You're seeing my raw data
    > as directly recorded and reduced so I apologize for the sloppy
    > writing. Some notes on my sight and workup:   I used water in the
    > artifical horizon box which caused some issues noted. With the
    > artifical horizon the raw hs is double a horizon sight (hsx2
    > column). I simply halved the hsx2 minutes for a spreadsheet plot not
    > shown, but do correctly show hs at LAN - 54°54.2'. For simplicity
    > this first time I did not correct hs to Ho, but looking at it now I
    > belive that r is the only correction I would need to make ( -1' from
    > table 6 in the Air Almanac). Lastly, being an aviator, I use the Air
    > Almanac for the GHA calculation for latitude.
    > For my NavList friends that are wondering where the bubble sextant
    > is - I retired a month ago, no more sights from the cockpit. I'm
    > going sailing in the San Juan's first of October with an old friend,
    > so I'm trying to quickly teach myself nautical techniques and picked
    > up a Davis MK25 to have some fun with. Hopefully you won't consider
    > Lat within 6 miles and Long within 22 miles too terrible for my
    > first try :)
    > Tracy
    > [plain text auto-generated]
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    > Attached File: http://fer3.com/arc/imgx/NoonSight07092020.pdf
    > View and reply to this message:
    > http://fer3.com/arc/m2.aspx/Longitude-noon-Shrier-sep-2020-g48523

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