NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Approximations
From: Peter Hakel
Date: 2010 Mar 10, 18:42 -0800
From: George Huxtable <george@hux.me.uk>
To: NavList@fer3.com
Sent: Wed, March 10, 2010 5:02:32 PM
Subject: [NavList] Re: Approximations: WAS: Star - Star Observations
I note the limit that Frank set, to altitudes above 45º, and agree
with it, but am not sure where Peter's 15º figure enters, in his "(altitudes
above 15 and 45 degrees, respectively)"
[parts deleted by PH]
From: Peter Hakel
Date: 2010 Mar 10, 18:42 -0800
Quoting from Frank's posting:
"And since the refraction is very nearly proportional to the tangent of the zenith distance for altitudes above 15 degrees, and since the tangent function is nearly equal to the angle for fairly small angles, the effect of refraction for altitudes above about 45 degrees is simple proportional compression."
Peter Hakel
"And since the refraction is very nearly proportional to the tangent of the zenith distance for altitudes above 15 degrees, and since the tangent function is nearly equal to the angle for fairly small angles, the effect of refraction for altitudes above about 45 degrees is simple proportional compression."
Peter Hakel
From: George Huxtable <george@hux.me.uk>
To: NavList@fer3.com
Sent: Wed, March 10, 2010 5:02:32 PM
Subject: [NavList] Re: Approximations: WAS: Star - Star Observations
I note the limit that Frank set, to altitudes above 45º, and agree
with it, but am not sure where Peter's 15º figure enters, in his "(altitudes
above 15 and 45 degrees, respectively)"
[parts deleted by PH]
