NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: h.a.c. van Asten
Date: 2013 May 6, 02:02 -0700
Mr.Hawes , many thanks for your appreciated information , it confirms (thank goodness) that I was right when a few years ago I stated that , if at sunset you use the bubble sextant (sun´s refracted centre in horizon) , whereas the next morning any different instrument (sun´s refracted U.L. in horizon) is operated without correction for time , you virtually shorten the precomputed night lenght by sun´s rise time ; virtually since the error can not be seen by the GMT watch time . The confusion is amplified if it so happens that at sunrise the sun´s rise time figure is equal to the Equation of Time figure . In the latter event the ´Equation´ figure must be doubled and added to the observed GAT of sunrise , before deciding for further DR operations , p.e. to plot the GMT for altering to an offset lane for finding an island by dog leg approach . hva
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