NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Latitude + Longitude @ Noon
From: Frank Reed CT
Date: 2005 Jun 6, 22:55 EDT
From: Frank Reed CT
Date: 2005 Jun 6, 22:55 EDT
Henry you wrote: "Forwarded for your further comment is the following posting of 31 Jul 2004, on the subject. I must say that your failure to respond, and for that matter the failure of this list to do so in general, was most dissappointing. I try only to post on practical navigation matters that I have tried or experimented with at sea and can only say that this list appears disinterested in such matters." I remember that post and enjoyed it. I thought you made your point well. Don't worry too much if a post doesn't draw follow-ups. There's no way to know who has read a particular message. People take vacations from lists like this. And there's no guarantee that a post will lead to a longer conversation. I've started a bunch of topics just in the past few weeks that didn't go anywhere... Your approach to lat/lon near noon is to do "equal altitudes" on either side of noon for the longitude. This works on exactly the same principle as the method I described, of course. The advantage that arises from shooting the Sun every five to ten minutes is that you have more data points and so random "noise" tends to average out. This is somewhat important since the rate of change in the Sun's altitude is very slow near noon. A one minute of arc error in a measured altitude could easily correspond to a one minute of time error in the estimate of noon (and thus 15 minutes error in the longitude). -FER 42.0N 87.7W, or 41.4N 72.1W. www.HistoricalAtlas.com/lunars