A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2013 Apr 8, 16:26 -0400
2008 & 2009 do NOT have those referenced equations.
I do thank you Paul for presenting them.
They do show
for 10C 1010mb humidity 80% wavelength 501.69 nanometers.
It shows the procedure for using A4 but no equations about how the values are derived
Marcel Tschudin wrote: > The refraction formula is indeed the one from Bennett in a form which > provides the resutls in degrees. Bennett provided also a second > formula for further improving the result of this first formula. Does > your N.A. 1998 edition makes reference to it? There's no reference to a more accurate formula. The formula (including the corrections for pressure and temperature) duplicates the almanac's high and low altitude refraction tables within 0.1′ for the values I tried, assuming 10 C and 1010 mb. I didn't test the almanac table A4 corrections for nonstandard conditions. > Just in case these finding should one day be documented in a paper: > How is the correct reference to this N.A. edition? 1998 Nautical Almanac Commercial Edition, published jointly by Paradise Cay Publication and Celestaire Inc., "Sight Reduction Procedures" chapter, p. 280. Does anyone have a newer almanac? Are the refraction and dip formulae still included? -- I filter out messages with attachments or HTML.
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