NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Taking four stars for checking accuracy of fix - and "Cocked Hats"
From: Geoffrey Kolbe
Date: 2008 Aug 03, 11:43 +0100
From: Geoffrey Kolbe
Date: 2008 Aug 03, 11:43 +0100
Ok Peter, I now see what you are saying. Thankyou for being patient and
explaining it.
What you are saying is that you can calculate how an altitude will vary with time and so you now have a line with the correct slope to fit to your data. This is an additional piece of information that simple averaging or statistical fitting by method of least squares, say, does not give you. Having got your line with the correct slope, you can draw a line parallel to this through your data points for a best fit. Yes, no doubt about it, this is superior to simple averaging as an extra piece of information is being included that was not there before.
Having plotted your data points on an altitude vs time graph, and also plotted the calculated line for your estimated position, the distance you have to move the line in the altitude axis direction to get a good fit with your sightings will be just Ho - Hc, the intercept distance along the azimuth.
Geoffrey Kolbe
--~--~---------~--~----~------------~-------~--~----~
Navigation List archive: www.fer3.com/arc
To post, email NavList@fer3.com
To , email NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
What you are saying is that you can calculate how an altitude will vary with time and so you now have a line with the correct slope to fit to your data. This is an additional piece of information that simple averaging or statistical fitting by method of least squares, say, does not give you. Having got your line with the correct slope, you can draw a line parallel to this through your data points for a best fit. Yes, no doubt about it, this is superior to simple averaging as an extra piece of information is being included that was not there before.
Having plotted your data points on an altitude vs time graph, and also plotted the calculated line for your estimated position, the distance you have to move the line in the altitude axis direction to get a good fit with your sightings will be just Ho - Hc, the intercept distance along the azimuth.
Geoffrey Kolbe
--~--~---------~--~----~------------~-------~--~----~
Navigation List archive: www.fer3.com/arc
To post, email NavList@fer3.com
To , email NavList-@fer3.com
-~----------~----~----~----~------~----~------~--~---
