NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Emergency sun declination
From: Frank Reed CT
Date: 2004 May 19, 18:32 EDT
From: Frank Reed CT
Date: 2004 May 19, 18:32 EDT
Jim T wrote:
"What about this method for emergency calcuation of declination?
1. Label a compass rose June 22 at 000o, Sept 23 at 090o, Dec 22 at 180o and
March 21 at 270o.
[...]
4. Error is +/- 0.5o."
Yep. Works great. Notice that this is really just a means of generating sines. Navigators in that era knew how to generate tables of sines and other trig functions (at using dividers and pencil and paper so they probably would have gone that more laborious route.
As with any method that approximates the ecliptic by the sine function, there are errors of about 0.5 degrees at the dates between the solstices and the equinoxes
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
"What about this method for emergency calcuation of declination?
1. Label a compass rose June 22 at 000o, Sept 23 at 090o, Dec 22 at 180o and
March 21 at 270o.
[...]
4. Error is +/- 0.5o."
Yep. Works great. Notice that this is really just a means of generating sines. Navigators in that era knew how to generate tables of sines and other trig functions (at using dividers and pencil and paper so they probably would have gone that more laborious route.
As with any method that approximates the ecliptic by the sine function, there are errors of about 0.5 degrees at the dates between the solstices and the equinoxes
Frank R
[ ] Mystic, Connecticut
[X] Chicago, Illinois
