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    Re: : David Thompson's Navigational Technique
    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.
    
    
    

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