NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Celestial Navigation without a sextant.
From: Peter Fogg
Date: 2008 Mar 9, 14:38 +1100
From: Peter Fogg
Date: 2008 Mar 9, 14:38 +1100
George wrote: > So timing sunrise/sunset will > never provide a precise value for longitude. But if a rough ball-park figure > will suffice, it could do the job. Here's a thought: if the time of apparent sunrise/sunset was observed regularly; the extent of the difference or inaccuracy shown by observation compared to calculated data could be evaluated on a regular basis and contrasted with other information about position. Given that the effects of anomalous refraction can constitute a significant constraint upon the accuracy of observations taken from the deck of a small boat, thus from within the lowest band of atmosphere, and that there is no way of knowing whether they are present, let alone the extent of inaccuracy introduced; If this known difference between observed and calculated sunrise/sunset should change, could it be a indication of the extent of anomalous refraction likely to affect sights taken close to that time, eg; star sights just before dawn, or just after sunset? Particularly sights taken in that direction? --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---