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    Re: Noonsite using artificial horizon? Did I do it correctly?
    From: Bill B
    Date: 2014 Aug 25, 18:06 -0400

    > How I determined LAN-
    >
    I do it one of two ways (sans cell phone).
    
    Online
    
    Go to:
    
    http://www.tecepe.com.br/scripts/AlmanacPagesISAPI.dll
    
    Click on "Navigator Star Finder" then enter you lat and lon as well as
    checking to see that the GMT date is correct. Click "submit." On the
    page that comes up click on "Sun" on the list to the right of the image
    and it will provide you with the GMT meridian passage (aka LAN for the
    Sun). It will also provide you with declination, GHA, LHA etc. for the
    specified time. (Be sure to adjust the GMT time to your time zone.)
    
    If you go back to the entry form and enter the time of meridian passage
    from the above (LAN) and repeat the above sequence you will see Hc,
    declination etc. for LAN.
    
    Nautical Almanac/west longitude
    
    * Go to the daily page for the current GMT date.
    * Locate the GHA closest to but less than your longitude.
    * Subtract that GHA from your longitude.
    * Divide the remainder by 15 with a calculator, being certain to convert
    between decimal degrees and degrees/minutes/seconds during the
    calculation; or use the arc-to-time table in the rear of the NA.
    * Add that to the whole hour UT time you used for the GHA and and adjust
    to your time zone.
    
    Example:
    
    * Longitude: 86d 14' 54" W
    * GMT date: 25 August 2014
    * Nearest GHA below longitude: 74d 29.3' at 17:00 UT
    * 86d 14' 54" - 74d 29' 18" = 11d 45' 36"
    * 11d 45' 36" / 15 = 00:47:02.4 by calculator
    * 11d 45.6'= 44 minutes + 3 minutes 2 seconds = 47 minutes 2 seconds
    using NA conversion of arc-to-time table
    * UT for LAN = 17:47:02 (17:00:00 + 00:47:02)
    * Adjusted to EDT (-4) = 13:47:02
    
    BTW
    
    * There is no dip correction for and artificial horizon (AH)
    * If you are making the bottom of the reflected limb tangent to the
    upper limb of the clear glass image, it is a lower limb sight and vice
    versa. I find limb-to-limb rather than trying to superimpose more
    accurate for me. Your mileage may vary.
    
    
    
    
    

       
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