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Subject: Re: Silicon Sea: Leg 71 (belatedly)
From: Noyce, Bill (William.Noyce@XXX.XXX)
Date: Tue May 29 2001 - 15:22:21 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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