NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Peter Fogg
Date: 2010 Dec 6, 19:13 +1100
Various people have been advocating plotting a line with the known slope, the rate of increase of the object's altitude
You can calculate this sloping line either by using a unique equation (not complicated, but you have to dig it up and remember it every time) OR, NEARLY AS EASY, and generally more accurate,
you can just calculate the Hc at some convenient time near the beginning of your set of sights and then calculate Hc again for a time near the end of the set of sights.
Using a system like this to detect and remove "outliers" (bad sights) is a tougher call, but definitely viable, as Peter Fogg has said, if the outliers are really far out of line. You can't just pare away any and all sights that are inconsistent with a nice line. You need to use a careful and rigorously applied system for removing bad sights,
and in many cases, it's better to keep all the sights since the appearance of an "outlier" may be an illusion, a random accident.
That's why any such removal system has to be decided on in advance and applied according to the rule without exception.