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George is wright except that I think that 0611 is the BEGINNING of civil
twilight (not the end of) for july 18th 2003 ;-)

Pierre Boucher

>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)      ??????
>
>=============
>
>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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