NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Andrés Ruiz
Date: 2010 Mar 18, 11:44 +0100
Dear Peter,
My results are:
B[0-90][+N/-S] L[0-180][+E/-W]
(41.715819121272141, -87.932112517443386) ( 41º
42.9' -87º 55.9') LopLSSR = 0
(41.715819121272148, -87.932112517443755) ( 41º 42.9'
-87º 55.9') KaplanSR_Bm = 0
DeWit/USNO
Nautical Almanac/Compac Data, Least squares algorithm for n LOPs
GHA DEC HO BO
LO LHA HC Z p
50.2093 -1.2202 35.1819 41.9600 -87.6350 322.5743 35.1810 131.9796 0.0009
50.8553 -1.2195 35.5656 41.9600 -87.6350 323.2203 35.5369 132.6404 0.0287
51.3387 -1.2190 35.8158 41.9600 -87.6350 323.7037 35.8007 133.1389 0.0151
51.8722 -1.2184 36.0493 41.9600 -87.6350 324.2372 36.0893 133.6929 -0.0400
52.4140 -1.2178 36.3829 41.9600 -87.6350 324.7790 36.3797 134.2597 0.0032
52.8724 -1.2173 36.6331 41.9600 -87.6350 325.2374 36.6233 134.7427 0.0098
53.3933 -1.2167 36.9166 41.9600 -87.6350 325.7583 36.8976 135.2953 0.0190
53.7559 -1.2163 37.1502 41.9600 -87.6350 326.1209 37.0870 135.6823 0.0632
54.3727 -1.2156 37.4003 41.9600 -87.6350 326.7377 37.4061 136.3452 -0.0057
54.8061 -1.2151 37.6672 41.9600 -87.6350 327.1711 37.6280 136.8144 0.0392
Estimate position
at time of fix:
Befix [deg] =
41.9600
Lefix [deg] =
-87.6350
Least Squares
information:
nObservations = 10
AA = 4.9057
BB = -4.9920
CC = 5.0943
DD = -0.0950
EE = 0.0935
FF = 0.0087
G = 0.0706
Error:
S = 0.0062
sigma = 1.6734 nm
sigmaB = 13.9479
sigmaL = 14.2134
Ellipse:
Prob = 0.9500
k = 2.4477
theta = 44.4592
a = 48.7271
b = 1.2957
Improved position
at time of fix:
dB [deg] = -0.2442
dL [deg] = -0.2971
DO [deg] = 19.7579
nm
BI [deg] = 41.7158
LI [deg] =
-87.9321
iteraciones = 1
The input file for the program is attached.
In your fortran program the transformation from Cartesian
coordinates is wrong, and the result you obtained is false.
See at my website my the paper: “Celestial Fix
- 2 LoP analytic solution”
Could you correct the program and give us the result?
Regards.
---
Andrés Ruiz
Navigational Algorithms
https://sites.google.com/site/navigationalalgorithms/
De:
navlist-bounce@fer3.com [mailto:navlist-bounce@fer3.com] En nombre de P H
Enviado el: jueves, 18 de marzo de
2010 2:35
Para:
Asunto: [NavList] Re: Today's
octant sights
Thank you for this data
set, Frank. I dug up my old rapid-fire-fix Fortran program, finally
addressed a little detail in it and, lo and behold, my "error bars"
became much smaller than before. As I suspected last year, the results
are indeed better than my "old" standard deviations would
allow. For your data set I calculate:
Latitude: N 41 deg
57.4' +/- 11.8'
Longitude: W 87 deg 43.1' +/- 16.0'
This result differs from your actual location by S 0.2' in latitude, and W 5.0'
in longitude.
@Antoine:
The source code and input file are attached. The program calculates the
crossings of all possible LOP pairs. Then it calculates the average
latitude and longitude, and the associated standard deviations.
Even in this case the "error bars" still appear to be unnecessarily
large. Suggestions of a more appropriate statistical procedure would be
welcome.
Peter Hakel
From: Frank
Reed <
To: NavList@fer3.com
Sent: Wed, March 17, 2010 2:32:01
PM
Subject: [NavList] Today's octant
sights
Here are
the Sun sights I took with an old ebony octant c.1840 this morning on the shore
of Lake Michigan:
10:29:00
35-00
10:31:35 35-23
10:33:31 35-38
10:35:39 35-52
10:37:49 36-12
10:39:39 36-27
10:41:44 36-44
10:43:11 36-58
10:45:39 37-13
10:47:23 37-29
Times are
CDT. The "watch" was 10 seconds slow, so add 05:00:10 to get to GMT.
These are all Sun LL (35-00 means 35 deg 00'). Index correction was 0 since
those old octants were supposed to be zeroed out every time. Height of eye was
"Rapid-fire"
fix anyone?
-FER
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