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Dear David,

If you are willing to use HO249 instead, I propose the following
method. It's not exact to the minute.

Look up the declination of the planet for the date you're interested
in and round to the nearest degree. Open HO249 on the page corresponding
to your latitude (whole degrees) and planet's declination, paying
attention to 'SAME' or "CONTRARY' signs for those values. Select the
right column for declination; in this column go up or down until
you find altitude Hc = -0;34 or as close to it as you can. On this line
you find two LHA's: one on the right and one to the left of the table.
Take out those LHA's and add (or subtract, depending on E or W) your
longitude. Now you have two GHA's which correspond approximately to the
GHA of the planet at rise and set. Look up those GHA's on the daily page
in the almanac under your planet to get the times of rise and and set. For
this you will have to do reverse interpolation.

If you insist on using HO229, you can follow essentially the same method,
but it is a lot more clumsy because HO229 has one LHA per page, so you
have to flip pages back and forth until you find Hc ~ -0;34 in the right
row and column.

Success,

_Steven.


-----------------------------------------------------------
Steven Wepster                          wepster@math.uu.nl
                                        tel +31 30 253 1186
Mathematisch Instituut
Universiteit Utrecht
PO Box 80.010
3508 TA Utrecht
The Netherlands
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