NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Rejecting outliers
From: Gary LaPook
Date: 2011 Jan 8, 10:54 0800
From: Gary LaPook
Date: 2011 Jan 8, 10:54 0800
But for calculating the slope the DR doesn't need to be particularly accurate as the slope is determined only by your latitude and the azimuth of the body, which you can measure to sufficient accuracy. If you scan the Motion Of the Body table from H.O. 249 at: http://www.fer3.com/arc/img/102321.mob%201.pdf you will see that the rate of change in altitude is very insensitve to errors in latitude and azimuth. For example, looking at the MOB table for my data where my DR latitude was 14° 25' and the azimuth was 103° true, the tabulated values for the change in altitude for one minute of time changed only 0.1' for a 2 degree azimuth change and by only 0.2' for a 5 degree change in latitude. So for a five minute observation period, if my DR latitude had been wrong by five degrees the slope would be off by only one minute of altitude. Similarily, the measured azimuth would have had to have been off by four degrees to produce a one minute error in the slope. Scanning H.O. 249, volume 2 shows that to produce an error of four degrees in the azimuth my DR longitude would have had to have been off by ten degrees, 600 nm! gl  On Sat, 1/8/11, P H <pmh099.com> wrote:
