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1990-04-14
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THE QUICK ALMANAC
Copyright (c) 1990 Philip Miller
v1.01 (04-10-90)
There are already numerous programs that give the current days sunrise
and sunset so why add another to the shareware pool?
I strongly feel it is not enough "to get the numbers right." Successful
programs must have an appealing and easy-to-read screen format, as well
as being informative.
This program is an adaptation of a program available from the US Naval
Observatory and is probably accurate for at least the next 60 years.
It is designed to be quite intuitive, as I dislike lengthy manuals
anyway.
What is added to this program are the transit times, which are those
times that the moon or the sun are directly over the meridian chosen, or
where the body is directly overhead. Also, the ambient atmospheric light
intensity as measured in lux ( as opposed to foot-candles ) are also
provided. These can be varied more accurately by changing the last option
(visibility) from "1" being the clearest to "10" being the most overcast.
One can readily appreciated the almost tenfold difference in ambient
light by varying these numbers. These may be of interest to
photographers.
On rare occasions a moon's rising, setting or transit time will actually
occur the following day. In these cases the times will have an 'f'
designation meaning the time is the following morning.
Using the pop-up window, one can quickly see the changing times through
the year as you vary the dates or times of visualization.
Latitude and longitudes are entered as degrees and decimal fractions of
degrees. Also by convention, degrees W (all locations in the US) are
written as negative. Therefore, 121W 30 is equal to -121.500 degrees
( 121.50 degrees west of Greenwich meridian ).
As currently released, the latitude and longitude will default to
Monterey, California coordinates. REGISTER YOUR COPY and you will be
provided with the means to set your own location as a default.
If the program is pushed to the extremes of latitudes, you will see that
either the sun rise and set times and/or the moon rise and set times will
fail to appear. This is because the formulas do not allow for precise
calculations of these skewed values. This will be at times when the body
in motion is tracking at too shallow an angle to the horizon, or when the
body is always above the horizon or always below the horizon and
therefore does not have a definite rise or set time.
One last technical point: programs that are math intensive such as most
astronomy programs, are executed much faster with a math co-processor. If
your system includes one, try entering "set 87=no" to see the difference
in speed with and without the co-processor. For the majority of those
that do not have an 80x87 you will see a pause after the pop-up window
while the program is calculating the results. I spent many years without
a co-processor but time has taught me that newer systems really are
optimized with math co-processors. I think they are worth the investment.
Look for further enhancements in future editions now being planned.