NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Averaging
From: Fred Hebard
Date: 2004 Oct 23, 00:05 -0400
From: Fred Hebard
Date: 2004 Oct 23, 00:05 -0400
Bill, Here is a graph of altitude versus time for meridian altitudes that vary from 15 to almost 90 degrees. The non-linearity is greatest in the graph for 75 degrees, and you can see that it's a pretty straight line by 50-75 minutes after passage. The non-linearity is less at 60 degrees but extends up to 100 minutes after passage. By 45 degrees, the curve is almost imperceptible, but of course there (otherwise the sun could never rise or fall!). At meridian passages of 90 degrees you can see the sun goes straight up, then straight down; my mistake the other day was looking at that curve rather than one a bit lower, such as 75 degrees. These curves show the sun going down after meridian passage. The curves for it going up before passage are mirror images extending to the left on the graph. Fred