A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2016 Jan 1, 08:55 -0800
The 6" slide rule seems to get close to 3 place precision which is enough to handle ex-meridian calculation needs. On ex-meridians within 30 minutes time of LAN the altitude is changing very little vs. time so meridian angle, declination, and latitude to the tenth of a degree is good enough for determining the minutes of correction to 2 places. The 6" slide rule is plenty good for calculating azimuth, amplitude, and prime vertical to within a few tenths of a degree as well.
As for lunars. The Hc can be calculated for the bodies in lieu of direct observation with the sextant. This Hc calculation doesn't need to be done as precisely as the rest of the lunar calculation. I will refer to Frank for a better explanation on this detail.
From: Francis Upchurch
Date: 2016 Jan 1, 00:57 -0800