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Guus Dekker asked-

>What is wrong with my computation about sunrise at Sao Paolo at july 18
>2003(three)
>lat: 24-20 S long: 47 W
>
>Nautical Almanac 2003
>
>20                6.11
>
>24,20            X
>
>30                6.27
>-------         --------
>10*              17 m          Dla = 24.20 - 20 = 4* 20'
>
>Table 1 page xxxii
>10-4.20-4.30-17-15 ---  corr. = 7 m             X= 6.11 + 7  =
>6h 18m
>
>
>
>
>long:                            =  47*
>47*/15* = (ZD)3 x 15* = 45*
>                                   ---------
>
>                            Dlo      2*       conv. arc to time page i
>2---                  8 m   (w=+)
>
>                            ----------------
>
>SUNRISE
>6h 26m
>
>(my navigator light 4.1. prog tells me the sunrise = at 6h 50m)      ??????

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Response from George-

Well, I have here a Nautical Almanac for 2001, not 2003. But on the same
day of the year, sunrise and sunset times aren't going to vary much from
one year to another.

It looks to me as if Guus Dekker has taken his times, not from the Sunrise,
but from the "end of Civil  Twilight" column. This precedes sunrise by
about 25 min, and gives the time when the Sun is about 5deg below the
horizon.

George.


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