A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Greg Rudzinski
Date: 2018 Nov 3, 03:40 -0700
I do averaging of index error using the horizon , Sun , star, or planet every time the sextant comes out of the box. Averaging of timed observations using a properly adjusted metal sextant is I think extra work if aboard a ship or on a small craft in good weather. If using a plastic sextant then averaging of sights would be advised. Plastic is not as stable or consistent as metal when exposed to temp changes or hand squeezing. Accuracy is improved with all sextants if three bodies are observed with 120 degrees of azimuth separation or four bodies with 90 degrees of azimuth separation. Systematic errors are equal and opposing. If altitudes are roughly the same then arc error is also equal and opposing. The size of the plotted square or triangle is of no consequence. I like sight reduction methods that use the DR/GPS position as an assumed position so that gross mistakes can be caught. Frequent gross mistakes can then be identified and guarded against on subsequent observations.
From: Bill Lionheart
Date: 2018 Nov 2, 07:40 -0700