NavList:

   

Reply

At 118*13'43"W the zone time of LAN was 120214 zt on 1-15-04.
1.In this experiment 1 sight was taken at the calculated time of LAN.
2.No.I was experimenting with a timed shot at a calculated time.
3.That was the only input period.
4.No azimuth was observed.As it was explained to me is how I tried it.
As I explained earlier,a person who had years working at sea once told me
one could do this in a pinch.I never tried it in real life.Because of the
reaction from some list members I decided to give it a "field test".I got my
1984 copy of Bowditch out to see if it was mentioned.There is a small
section mentioning if the sight is taken at the time when the Sun is
centered on the local meridian the GHA of the Sun will equal the longitude
of the observer.I tried it and posted the results.
I will tell you guys if in the future conditions or circumstances are such I
will use it.
--Original Message-----
From: Navigation Mailing List
[mailto:NAVIGATION-L@LISTSERV.WEBKAHUNA.COM]On Behalf Of Noyce, Bill
Sent: Friday, January 23, 2004 05:30
To: NAVIGATION-L@LISTSERV.WEBKAHUNA.COM
Subject: Re: Timed Noon sights for position


> Bill,I don't understand what you're try to convey.
> If you took the noon sight while the DR was 30 m to
> the east the resulting GHA of the Sun would reflect
> that.The 120414zt time is only valid for the one EP.

No, I wanted to take the noon sight when the EP was the
same, but the *true* position was far from the EP, to
see whether the sight would reveal that my EP was bad.
I tried to work through what the observation would be
in that case, and what the calculated latitude and
longitude would be.  Latitude came out within about a
mile of right, but longitude simply parroted the EP's
longitude.  But perhaps I didn't understand.

 - Do you take just one sight, aiming for the time
   that you calculated for LAN?

 - Or do you track the sun's rise and try to record the
   time at which it reaches a maximum?

 - What values provide the inputs for your longitude
   calculation?  From your worksheet, it looks as if
   the major input is the pre-calculated time of LAN
   at the EP.  Is that a correct interpretation of
   your procedure?

        -- Bill

   

Reply