Astronomical Clock for the Psion 3a/3c

Version 1.1

Purpose

Sidereal may be of interest to anyone who wants to know the local Sidereal time, or the local sundial time. It has two display modes, the first presents a large simulation of a LCD digital clock, this can be configured to show a number of different clocks. The second mode has a tabular display of all the clocks available on the digital display, plus some other values such as the Julian Date, and the current value of the equation of time.

Features

Main Digital Display

	Local Mean Sidereal Time.
	Greenwich Mean Sidereal Time.
	Local Mean Time.
	Local Apparent Time.

Secondary Digital Display

	Universal Coordinated Time.
	Local Civil Time.
	Local Zone Time.

Tabular Display

	Equation of Time.
	Day of year.
	Julian Date.
	Modified Julian Date.

General

Sidereal 'sleeps' when running in the background, this makes your other applications more responsive.

Installation

Copy Sidereal.OPA to the APP directory, then use <Psion><I> to install the icon.

Limitations

This release will only run on the Psion 3a and 3c models. Later versions may support the Sienna and the Psion 5.

The calculation used for the Equation of Time is not very accurate, but I've been unable to find a definitive solution, do you know any better?

You can email me at the following address "mark (dot) crossley (at) dsl (dot) pipex (dot) com" to send me any comments.

 Notes

Sidereal is fairly CPU intensive (I find it uses about 40% of the total available CPU time on my 3a) when in the digital display mode. This could have an impact on your battery life, if you wish to use Sidereal for prolonged periods then I suggest you use an external power supply. When Sidereal is not the foreground task it suspends and does not use any CPU time.

Versions

1.0 First public release.

1.1 Added Modified Julian Date to tabular screen.

Download

You can download the latest version of Sidereal from here: sidereal.zip