NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Refraction:Which formula for Heights below 15°
From: Herman Dekker
Date: 2022 May 16, 13:26 -0700
From: Herman Dekker
Date: 2022 May 16, 13:26 -0700
Hello Navigators,
One question about calculation refraction.
If the measured altitude (h) is <15° I learned in Franks Advance Moderen Cel.Nav. Workshop:
I: R=1.0’/Tan [h+6.82/(h+4.024)]
In Henning Umland’s “A Short Guide to Cel.Nav.” the used formula is:
II: R=1.0’/Tan[h+7.31/(h+4.4)]
Can you explain the difference values?
If I calculated f.i. for h=0°,1°, 5° and 10° the calculated values are:
h= 0° 1° 5° 10°
I: 33.79’ 24.29’ 9.92’ 5.40’
II: 34.47’ 24.32’ 9.88’ 5.39’
The difference is negligible. but where come the different values in the formula from?
Regards.
HermanD
