NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Refraction correction
From: Marcel Tschudin
Date: 2009 Apr 14, 13:01 +0300
From: Marcel Tschudin
Date: 2009 Apr 14, 13:01 +0300
Peter, The refraction tables are generally made based on a standard atmosphere and assuming "astronomical viewing conditions". Refraction depends on the temperature gradients in the atmosphere, temperature and pressure but also - and this is important - on the angle of incidence of the viewed ray. This is the reason for not doing astronomical measurements below about 5 degrees altitude. The presence of clouds may cause various different disturbances of the viewed ray, which - depending on the situation - may more or less disturb the measurement. This would require a distinction between critical and non-critical cases. I don't know if someone already has looked into this in more detail. Marcel --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
