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Re: Time of meridian passage accuracy
From: Gary LaPook
Date: 2009 Sep 30, 21:19 -0700
This hypothetical takes place on December 22, 2009 and the sights are taken at five minute intervals on the exact five minute mark and all sextant corrections have been applied so the values stated are the observed altitudes, Ho. They cover a two hour period from 1700 Z to 1900 Z.
17:00:00 42º 14'
:05 42º 44'
:10 43º 13'
:15 43º 39'
:20 44º 04'
:25 44º 26'
:30 44º 47'
:35 45º 06'
:40 45º 22'
:45 45º 36'
:50 45º 49'
:55 45º 59'
18:00:00 46º 06'
:05 46º 12'
:10 46º 15'
:15 46º 16'
:20 46º 14'
:25 46º 10'
:30 46º 04'
:35 45º 56'
:40 45º 45'
:45 45º 33'
:50 45º 18'
:55 45º 01'
19:00:00 44º 41'
The D.R. at 1700 Z is 24º 25' N, 79º 50' W.
The course is 180º True.
The ground speed is 300 knots.
gl
James N Wilson wrote:
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From: Gary LaPook
Date: 2009 Sep 30, 21:19 -0700
Jim Wilson wrote on Sept. 26th:
"I compiled a table in my Navigation paper showing differences between maximum alititude and meridian passage ranging from 10 seconds to 37 minutes. My trial which led me to write the paper had a difference of a minute and a half, and that was at a moderate latitude and sailboat speeds."
I am curious how well it works at higher speeds. I have created a data
set and I would like you to evaluate it and tell me the time of
meridian passage, the longitude and the latitude at meridian passage."I compiled a table in my Navigation paper showing differences between maximum alititude and meridian passage ranging from 10 seconds to 37 minutes. My trial which led me to write the paper had a difference of a minute and a half, and that was at a moderate latitude and sailboat speeds."
This hypothetical takes place on December 22, 2009 and the sights are taken at five minute intervals on the exact five minute mark and all sextant corrections have been applied so the values stated are the observed altitudes, Ho. They cover a two hour period from 1700 Z to 1900 Z.
17:00:00 42º 14'
:05 42º 44'
:10 43º 13'
:15 43º 39'
:20 44º 04'
:25 44º 26'
:30 44º 47'
:35 45º 06'
:40 45º 22'
:45 45º 36'
:50 45º 49'
:55 45º 59'
18:00:00 46º 06'
:05 46º 12'
:10 46º 15'
:15 46º 16'
:20 46º 14'
:25 46º 10'
:30 46º 04'
:35 45º 56'
:40 45º 45'
:45 45º 33'
:50 45º 18'
:55 45º 01'
19:00:00 44º 41'
The D.R. at 1700 Z is 24º 25' N, 79º 50' W.
The course is 180º True.
The ground speed is 300 knots.
gl
James N Wilson wrote:
Douglas:You state that "the effect is very small as to be of no practical concern to practical navigators."I compiled a table in my Navigation paper showing differences between maximum alititude and meridian passage ranging from 10 seconds to 37 minutes. My trial which led me to write the paper had a difference of a minute and a half, and that was at a moderate latitude and sailboat speeds.Jim Wilson
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Or post by email to: NavList@fer3.com
To , email NavList-@fer3.com
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