NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Dave Walden
Date: 2011 Aug 19, 18:36 -0700
It REALLY does work!
Here's a case generated with Frank's online calculator. (No NOVAS, no JPL) I have no knowledge of what refraction calculation he uses. I pick a time and place and iterate on LD until I get zero error for each of the three stars. I do near and far, then average since I'm dealing with centers at the moment. I use his almanac data. I round the LD's to the nearest 10th of a minute. Seems like a pretty fair test. I get within 20 seconds and 10 nm starting from an hour off in time and 70 miles off in AP. Not bad for the 10th of a minute LD and linear interpolation between hours.
Nautical Almanac Data for August 16, 2011
Date and Times are GMT.
16:00 17:00
Moon's HP 54.39 54.38
GHA Aries 204° 42.1' 219° 44.6'
Greenwich Hour Angle
and Declination
The Moon 210° 23' 21" 224° 58' 11"
N 3° 1' 42" N 3° 13' 24"
Fomalhaut 220° 7' 9" 235° 9' 37" LD 33d 23.6m
S 29° 33' 21" S 29° 33' 21"
Hamal 172° 44' 14" 187° 46' 42" LD 41d 58.2m
N 23° 31' 5" N 23° 31' 5"
Markab 218° 21' 27" 233° 23' 55" LD 14d 59.0m
N 15° 16' 16" N 15° 16' 16"
(used 50d F, 29.83 in Hg, 0 IC, 0 ht of eye, include both corrections)
with LD's the the second (which Frank's calc can do):
time err -4.6s
lat err .1 nm
long err 3.1 nm
for those who are doing it:
33d 23m 45s
41d 58m 14s
14d 59m 1s
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