NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Andrew Seligman
Date: 2013 Sep 17, 21:14 -0400
U.S.C.G. Licensed Master
Certified ASA Sailing Instructor
215-514-6724
Hi Herb,This is where I get lost.if the 5 seconds is positive, then 12:00:00 + 00:00:05 = 12:00:05. How did you get from 12:00:05 to 11:59:55?Captain Andrew F. Seligman
U.S.C.G. Licensed Master
Certified ASA Sailing Instructor
215-514-6724
On Sep 17, 2013, at 7:59 PM, Herbert Prinz wrote:Andrew,
Yes, it is positive. But in the N.A. of 1995 (and all of them since 1925, if I am not mistaken),
"positive EoT" means that you have to add it to mean time to obtain apparent,
see p. 260 of the N.A.
It could as well be the other way round. This convention is as arbitrary as the one that positive values have a white background and negative ones are shaded. There is absolutely nothing to understand. That's why I can't remember either of these conventions and rather derive the result by analogy from the the tabulated meridian passages. That's anyway the sole purpose of those entries, because otherwise they are redundant.
But if you must: Add 5 sec to mean 12:00:00 to get apparent 12:00:05. Now, if by the sun dial it is 12:00:05 at this moment, the sun must have passed the meridian 5 seconds ago, so that would have been 11:59:55 mean time.
Herbert
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------
