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Subject: Re: Silicon Sea: Leg 72 -NEW
From: Sam Chan (schan@XXX.XXX)
Date: Sun May 27 2001 - 01:27:59 EDT
----- Original Message -----
From: "Dan Hogan" <dhhogan@XXX.XXX>
To: <NAVIGATION-L@XXX.XXX>
Sent: Saturday, May 26, 2001 12:36 PM
Subject: Re: Silicon Sea: Leg 72 -NEW
Dan,
For unknown body #1, the compass bearing was 349.7.
Using Can Dead Man Vote Twice At Election, correcting from
compass to true requires easterly variation and deviation be added to
compass. The variation was 10dW and deviation was 1dE, totaling 9dW.
With a compass bearing of 349.7 and subtracting 9d (since it is W)
results in 340.7. There is nothing near that location in the sky.
I noticed that if I added instead of subtracting the compass corrections,
the location fits Polaris and Deneb, thus my initial question to you to
check the
compass bearing. I figured that you started off with true bearings and
converted
them to compass.
Sam
> On 26 May 2001, at 13:43, Michael Wescott wrote:
>
> > > 6) What are the names of the two unknown bodies?
> > > -- ---------------------------------------------
> >
> > Unknown #1:
> >
> > 349.7 + 10 - 1 = 358.7d
> >
> > almost due north and altitude is about same as our latitude:
> > got to be Polaris
>
> Right
>
> > Unknown #2:
> >
> > 327.3 + 10 - 1 = 336.3
> >
> > This is visually in the angle between Polaris to the north and Vega
> > to the northwest. GHA Aries is about 34d and Long is 67W so zenith
> > has SHA of about 33d. Looking at the starchart in the almanac, there
> > is only one navigational star between Vega and Polaris: Deneb
>
> Right
>
> > > 7) What is the TC and Distance to the Aruba Gap (13d 50.0'N 70d
00.0'W)
> > > waypoint from our FIX?
> >
-- ---------------------------------------------------------------------
> >
> > dLat = 13d50.0' - 13d30.5' = 19.5'
> > dLo = 70d00.0 - 66d59.5' = 180.5'
> > dep = 180.5*cos 13d40' = 175.4
> >
> > TC = 270 + atan(19.5/175.4) = 276.3
> > Dist = sqrt(19.5^2 + 175.4^2) = 176.5
>
> OK
>
>
>
> Dan Hogan WA6PBY
> Catalina 27 "GACHA"
> dhhogan@XXX.XXX
> Navigation-L List Owner
> http://www.wa6pby.com
>
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