NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: V-Correction for Sun?
From: Stan K
Date: 2016 Oct 16, 16:23 -0400
From: Stan K
Date: 2016 Oct 16, 16:23 -0400
I remember a discussion we had a while back about what we would have like to see the Nautical Almanac do about the v issue. I seem to recall that the option that would require the least amount of space (of which there is really none at all) is to use the v value for 1200 UT of the middle day of the page, like the v and d values of the planets or the SHA and Dec of the stars. Perhaps the v value would be more useful than the SD?
Which makes me ask, Herbert, does you program use the date and time of the sight, or 1200 UT of the middle day of the page, for v values of the planets, etc.? I know it rarely makes a difference, but I'm curious. I put both options in Celestial Tools.
Stan
-----Original Message-----
From: Robin Stuart <NoReply_Stuart@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Sun, Oct 16, 2016 11:05 am
Subject: [NavList] Re: V-Correction for Sun?
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From: Robin Stuart <NoReply_Stuart@fer3.com>
To: slk1000 <slk1000@aol.com>
Sent: Sun, Oct 16, 2016 11:05 am
Subject: [NavList] Re: V-Correction for Sun?
Herbert,
I've been travelling for the last couple of days. Thanks for clarification. It seems to me that the adjustments in the NA may do more harm than good. Unadjusted values on the hour would permit accurate linear or non-linear interpolation to be performed. The current tables mean that the user can never be sure of what the GHA of the Sun is to the nearest 0.1' at any time of the year. Overall it might be better if the NA made no adjustment and published a v correction for the Sun which you could choose to ignore.
The thought did occur to me that the adjustment could be done by minimizing the root-mean-square difference of the true GHA from that obtained for each second in the hour using the Almanacs Increments and Corrections tables (including all the warts mentioned by Sean and Stan).
Regards,
Robin Stuart
PS My recent sojourn took me to the New Bedford Whaling Museum which has a diorama depicting the Charles W. Morgan in action, a half size model of a whaling ship and this guy
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