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cdeagle
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Joined: 22/06/2014
Location: United States
Posts: 261

Posted: 07:18am 15 Mar 2017

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This post is an MMBASIC computer program for the MicroMite eXtreme which can be used to predict the local circumstances of lunar eclipses. The software uses a combination of one-dimensional minimization and root-finding to calculate these conditions.

Here's a typical user interaction with the software. The program will take a minute or so to run to completion. Be patient, it's performing thousands of hardware-based, double precision calculations looking for the answer. The source code listing is 3200+ lines of comments, data statements, white space and actual code.

program lunar_eclipse
=====================

please input the initial calendar date

(month [1 - 12], day [1 - 31], year [yyyy])
< for example, october 21, 1986 is input as 10,21,1986 >
< b.c. dates are negative, a.d. dates are positive >
< the day of the month may also include a decimal part >

? 12,1,2000

please input the geographic latitude of the observer
(degrees [-90 to +90], minutes [0 - 60], seconds [0 - 60])
(north latitudes are positive, south latitudes are negative)
? 39,40,36

please input the geographic longitude of the observer
(degrees [0 - 360], minutes [0 - 60], seconds [0 - 60])
(east longitude is positive, west longitude is negative)
? -104,57,12

please input the altitude of the observer (meters)
(positive above sea level, negative below sea level)
? 1644

please input the search duration in days
? 30

searching for lunar eclipse ...

Here's the program output for this example.

total lunar eclipse
===================

begin penumbral phase of lunar eclipse
--------------------------------------

calendar date January 21 2000

UTC time 2 hours 2 minutes 51.52 seconds

UTC julian day 2451564.58531852

topocentric coordinates

lunar azimuth angle 83 deg 3 min 50.49 sec

lunar elevation angle 22 deg 43 min 45.01 sec

greatest eclipse conditions
---------------------------

calendar date January 21 2000

UTC time 4 hours 43 minutes 27.56 seconds

UTC julian day 2451564.69684679

topocentric coordinates

lunar azimuth angle 111 deg 22 min 33.61 sec

lunar elevation angle 52 deg 6 min 11.99 sec

end penumbral phase of lunar eclipse
------------------------------------

calendar date January 21 2000

UTC time 7 hours 24 minutes 8.60 seconds

UTC julian day 2451564.80843287

topocentric coordinates

lunar azimuth angle 184 deg 39 min 40.61 sec

lunar elevation angle 69 deg 27 min 51.25 sec

event duration 5.35474459 hours

Here's a zip archive of the MMBASIC source code and MATLAB PDF file for the lunar eclipse computer program.

2017-03-15_171630_lunar_eclipse.zip

Geoffg