NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Antoine Couëtte
Date: 2010 Mar 12, 08:20 -0800
Hello to all,
There is an EXCELLENT refraction formula which gives refraction as function of unrefracted topocentric altitude.
Its use would simply avoid the requirement for the "loop computation" you have explined.
This formula is the so-called Saemundsson's formula which can be found on the Internet. Its accuracy is well under 6 arc-seconds.
It is also quoted in M. Jean Meeus's most celebrated book "ASTRONOMICAL ALGORITMS" in its Chapter on atmospheric refraction.
Best Regards to you all
Antoine M. Cou�tte
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