A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Position-Finding
From: Gary LaPook
Date: 2018 Nov 5, 13:43 -0800
I made the sugestion several times in the past that the way to avoid all the discussion and desention about finding the proper point to represent the "fix" in a three-star "cocked hat" was simply to only observe two stars. It appears that this is the method used by the Air Force in its automated star-tracker systems, only using two stars at a time. And it acheives better than a 1,000 foot CEP. This means that 50% of the fixes will be within 1,000 feet, 93,7% will be within 2,000 feet, and only 0.2% will fall outside of 3,000 feet. The automatic star tracker is sugested for surface Navy ships but, for surface navigation, the same old problem of clouds raises its ugly head. At 25,000 feet the probability of a clear line of sight anywhere on earth and at any time is 68% and becomes 100% at higher altitudes. Would it were it this good on the surface!