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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Basics of computing sunrise/sunset
From: Christian Scheele
Date: 2009 Jun 19, 20:14 +0200
From: Christian Scheele
Date: 2009 Jun 19, 20:14 +0200
Many thanks, Frank, for the clarifying words on the limits of computing sunrise/set times. Being a function of athmospheric conditions at any possible point on earth, refraction values, I admit, remain estimates, however good. But in theory: Assume you know the athmospheric conditions to "the horizon" and beyond right up to GP of the sun, i.e. you are able to monitor these conditions for this entire stretch; say you have an imaginary string of weather balloons thousands of miles long. Would that solve refraction? Then other problems remaining would include anomalies in the curvature of the earth's surface, errors in the observer's height and sextant errors. "The same calculation is used for inland locations as for locations with a sea horizon." Sunset yesterday from my raised point of observation, the horizon being at sea level, was 3 minutes later than the time calculated for an observer at seal level. Christian Scheele --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
