A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2017 Jun 30, 03:16 -0700
The clue is not about the floating point precision or "battle of the apps".You have not been able to intuit the essence of the problem and its solution.
more approaches to the Fix?
Are you reminding us that by observing three stars with an azimuth spread of only 96degrees, it’s a bit like plotting a fix from three relative bearings on the same side of the ship/aircraft? I.e. if there is a significant coefficient A error in the compass, the real position of the ship/aircraft stands a strong chance of being outside the cocked hat. In the example given, the systematic error is in all the intercepts being wrong by a given amount, possibly as much as 30’ towards. As Greg says, the solution is to pick a better spread of azimuths. At least it would tell you something was wrong. Captain ‘Navigator’ says there wasn’t a lot to the SW that date and time, but Achernar (which even has a little diamond against it in AP3270 for 11S LHA Aries 069) Az 207, mag +0.6 might have been a better choice than Pollux Az 048, mag +1.2. DaveP