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John -

I'm not sure I understand your table. It seems to say that for a given
declination the sunrise bearings would be different for folks in
different hemispheres. On any given day doesn't the sun rise in the
same direction, no matter whether you're looking at it from the
Southern hemisphere or the Northern?

What's different is the time of sunrise.

For instance, using dec N22 and lat 34N,  your table gives
(interpolating by eye) a Z of 63�. By your rule for North Lats, Zn = Z
= 63�.

Looking in HO 260, page 81 which is for dec same name as lat, I find
azimuth 63� 08' at 4:53 a.m. So  your rule checks.

But, for someone at 34S when dec is N22, HO 260 page 190 which is for
dec contrary name to lat, I find azimuth 116� 52' at 7:03  a.m. The
rule at the bottom of the page says to subtract this azimuth from
180�. Rounding 116� 52' to 117� and applying this rule gives a true
bearing of 63�.

However, your rule,(South Latitudes: Sunrise  Zn = 180 � Z) as I
understand it, would in this case subtract 63� from 180� to give a
sunrise bearing of 117�.

This seems to mean that on the day the sun's dec is N22 someone in the
Southern hemisphere would see the sun rise to the south of east
whereas someone in the Northern hemisphere would see it rising north
of east?

Since Amplitudes have come up in this thread, I looked at Bowditch
Table 27 in my 1976 (Green) edition.  The amplitude for dec 22� lat
34� is 26.9�. Amplitudes are applied to 90� (E) if the sun is rising.
If dec is N they are subtracted from 90�.

So, rounding 26.9� to 27� and subtracting gives again a sunrise
bearing of 63�. Doesn't matter whether you're north or south of the
equator. When the sun is north of the equator it rises north of the
equator.

Hewitt

On 6/2/10, John Karl  wrote:
>
>
> OK, Maybe I've got it now (I read the instructions).
> JK
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