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This HP Prime computer program can be used to predict the local circumstances of solar eclipses. The program requires a calendar date at which to begin the search and the search duration in days. It also requires the geographic coordinates of an observer.

The software uses a combination of one-dimensional minimization and root-finding to perform the calculations. The program requires some time to run because it is performing numerous mathematical calculations.

Here's the program output for a calendar date and location "hardwired" in the software. The attached zip file also includes a PDF document that explains more about the algorithm.

LOCAL CIRCUMSTANCES OF SOLAR ECLIPSES

begin penumbral phase of solar eclipse

calendar date Dec 25, 2000

UTC time 15 hr 29 min 24.288 sec

julian date 2451904.14616

topocentric coordinates

lunar azimuth angle 132.358771949 degrees

lunar elevation angle 10.7478199442 degrees

solar azimuth angle 132.338786791 degrees

solar elevation angle 10.2288418565 degrees

greatest eclipse conditions

calendar date Dec 25, 2000

UTC time 16 hr 43 min 33.024 sec

julian date 2451904.19765

topocentric coordinates

lunar azimuth angle 146.918739896 degrees

lunar elevation angle 19.6965886601 degrees

solar azimuth angle 147.124792735 degrees

solar elevation angle 19.4627836401 degrees

end penumbral phase of solar eclipse

calendar date Dec 25, 2000

UTC time 18 hr 6 min 3.744 sec

julian date 2451904.25495

topocentric coordinates

lunar azimuth angle 165.917863746 degrees

lunar elevation angle 25.8631599307 degrees

solar azimuth angle 166.476742828 degrees

solar elevation angle 25.7455324751 degrees

event duration 2 hr 36 min 39.456 sec
The attached zip file is a slightly updated version of the solar eclipse prediction program for the HP Prime.

It will take some time to run to completion. The program consists of almost 3000 lines of source code and comments.
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