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Re: : David Thompson's Navigational Technique
From: Ken Muldrew
Date: 2004 Jun 1, 09:47 -0600
From: Ken Muldrew
Date: 2004 Jun 1, 09:47 -0600
On 1 Jun 2004 at 13:27, George Huxtable wrote:
> Ken Muldrew wrote, about observations in October 1800-
>
> The longitude by
> >account gives a time of about 7 hours 39 minutes so Greenwich time
> >would be about 4:26 on the 12th. The online Nautical Almanac gives a
> >sun declination of 7? 29' S for this time and date, exactly in accord
> >with what Thompson writes.
>
> ==============
>
> Could Ken please be a bit more specific about what he looked up in the
> online Nautical Almanac for 1800, which presumably works in terms of
> the modern civil definition of GMT?
>
> Did he actually enter a value for GMT into that online almanac of 04h
> 26m on 12 Oct 1800, and did that give him a Sun declination of 7deg
> 29'S?
4:26PM - ~13' equation of time gives 16:13. The sun values from the
online nautical almanac are:
1800 OCT. 12, 13, 14 (SUN, MON, TUE)
------+-------------------+-----------------------
| SUN | MOON
------+-------------------+-----------------------
G.M.T | GHA Dec | GHA v Dec
d h | ? ' ? ' | ? ' ' ? '
12 0 | 183 20.0 S 7 13.8 | 257 22.1 10.6 N25 19.8
1 | 198 20.1 S 7 14.7 | 271 51.8 10.6 N25 12.6
2 | 213 20.3 S 7 15.7 | 286 21.5 10.7 N25 05.2
3 | 228 20.4 S 7 16.6 | 300 51.2 10.7 N24 57.7
4 | 243 20.6 S 7 17.6 | 315 20.9 10.8 N24 50.1
S 5 | 258 20.7 S 7 18.5 | 329 50.7 10.8 N24 42.4
U | |
N 6 | 273 20.9 S 7 19.4 | 344 20.6 10.8 N24 34.5
D 7 | 288 21.0 S 7 20.4 | 358 50.4 10.9 N24 26.5
A 8 | 303 21.2 S 7 21.3 | 13 20.3 10.9 N24 18.4
Y 9 | 318 21.3 S 7 22.3 | 27 50.3 10.9 N24 10.2
10 | 333 21.5 S 7 23.2 | 42 20.3 11.0 N24 01.8
11 | 348 21.6 S 7 24.2 | 56 50.3 11.0 N23 53.4
| |
12 | 3 21.8 S 7 25.1 | 71 20.4 11.1 N23 44.7
13 | 18 21.9 S 7 26.0 | 85 50.5 11.1 N23 36.0
14 | 33 22.1 S 7 27.0 | 100 20.6 11.1 N23 27.2
15 | 48 22.3 S 7 27.9 | 114 50.8 11.2 N23 18.2
16 | 63 22.4 S 7 28.9 | 129 21.0 11.2 N23 09.1
17 | 78 22.6 S 7 29.8 | 143 51.3 11.3 N22 59.9
Ken Muldrew.
