NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Lunar distance presetting exercise
From: Antoine Couëtte
Date: 2019 May 27, 00:58 -0700
From: Antoine Couëtte
Date: 2019 May 27, 00:58 -0700
Dear Peter,
You wrote:
"That said, nautical refraction formulae and tables are built for sea level, whereas I am at an elevation of 7320 feet (2230 m); I don’t recall right now how much difference that makes for altitudes (perhaps aircraft pilots on NavList can comment), and I believe that it is academic for lunar distances."
At your altitude (2230 m), the standard atmosphere pressure is 75% of the pressure at sea level. Hence at the first order the refraction value at 2230 m should be 3/4 of the sea level values. And for the purpose of presetting Sun and Moon together into a sextant ocular, yes ... " [taking in account such change in refraction] is academic for lunar distances ".
Best Friendly regards,
Antoine
