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    Re: Silicon Sea: Leg 71 (belatedly)
    From: Bill Noyce
    Date: 2001 May 29, 15:22 EDT

    > > Using the above DR position,
    > >
    > > Body      Fomalhaut    Polaris       Deneb        Vega
    > > GHA       36d  3.0'   342d 53.1'    70d 20.8'   102d  8.4'
    > > Decl    S 29d 36.9'  N 89d 16.1'  N 45d 16.8'  N 38d 47.0'
    > > Hc        39d 50.8'    13d 23.4'    57d 23.5'    47d  5.2'
    > > Az        149.1d         0.7d       350.4d       313.9d
    > > Int        58.2' T      14.8' A      32.4 A       75.0' A
    >
    > Hmmm...something very wrong with the Polaris Dec. CAN'T be that high.
    What Dec. would you use for Polaris on 30 May?
    > Polaris gives your latitude with its LOP.
    AP Latitude  = 13d 15.8'
    Intercept    =     14.8' A
                  ---------
    FIX Latitude = 13d  1.0'
    I did it the long way because I'm not using Polaris tables:
    > > Pretty long intercepts, and a poor cut.  I used Ageton's
    > > method, and for Polaris found why it's not recommended for
    > > LHA near 90 degrees with high declination -- you end up
    > > trying to find an angle whose sine is about 1.0, and since
    > > the function doesn't vary rapidly there, the angle isn't
    > > established with any precision.  So instead of using
    > >       sin K = sin decl / cos R
    > > I tried
    > >                               cos T * sin R   cos T * cos d
    > >       cos K = cot T * tan R = ------------- = -------------
    > >                               sin T * cos R       cos R
    > > Is this Sadler's modification to Ageton's method?
    > > Anyway, I tried again with an AP of 13d 0' N 61d 30' W
    > > and got intercepts of
          [mostly under 0.5']
    > > and except for Mars, it looks like we're there.
    >
    > ??? FIX
    Sorry, I should have spelled it out.  With those small intercepts,
    I was willing to take FIX = AP (13d 0' N 61d 30' W).
    > > > 4)   What is the TC and Dist from our FIX to the Aruba Gap
    > > TC = 275.7d  Dist = 499 nm
    >
    > Hmm, TC is off. Check the FIX.
    Looking at your revised answer sheet, you have 286.8d for both
    #4 (TC) and #5 (CC).  I think that's the correct CC, and hence
    can't be the correct TC.
    > > > 5)  What is the Compass Course(CC)/Course-to-Steer for Aruba Gap?
    > > > --  -------------------------------------------------------------
    > >
    > > TVMDC, West is Best, add 11d: 286.7d
    >
    > OK
    

       
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