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Andrew Gregory's Web Pages

Sherbrooke Forest, 37°53'3"S 145°21'4"E


Astronomical Calculations 3a 3c 3mx Siena Workabout mx

This page collects together some useful astronomical-related calculations I have come across.

Also available here is a Date (Calendar) Conversion program by . It comes with full source and one of the files is an excellent collection of procedures to do all sorts of things...

Check out:

Sunrise / Sunset

Sunrise / Sunset

Why write a program to calculate sunrise / sunset times when the Psion can already do it? Because I also wanted twilight times to be calculated.

Juergen Galupki has written a 'front-end' to this calculation for the Siena. A small modification allows it to work on other machines too. See his web page: http://galupki.de/psion.html.

New in the 1999-03-11 release:

  • Summer time support has been added to the example (thanks to Juergen Galipki)
  • The RISET.OPL program
Derived From: Code written by Michael E Bakich.
Download: sunrise1.zip (4K)
Required Modules: None

Sunrise / Sunset

Sunrise / Sunset
Description: Similar to above routine, this can be used to calculate sunrise/sunset times, including twilight times. However, it does not use lookup tables and is therefore smaller and (most likely) faster.
Derived From: http://www.best.com/~williams/sunrise_sunset_algorithm.htm
Almanac for Computers, 1990
published by Nautical Almanac Office
United States Naval Observatory
Washington, DC 20392
Download: sunrise2.zip (2K)
Required Modules: None