Assuming you've managed to download it ok, theres only one screen and this is it.

The top pane shows a styalised view of the horizon, looking South. The tall vertical line is due South, left and right are the East and West compass points. North is behind.

The calandar starts off at the current date, read from your computer, with my home location, Stroud, England
Latitude 51 degrees 45 minutes (North)
Longitude 2 degrees 12 minutes West

To change your location, click in the box and type the numbers. Theres no error checking so dont be surprised if odd things happen at the north pole and at low Latitudes when the moon moves towards the North!

You can save the new location by clicking "Save Lat/Long"

Changing the date is easy, by clicking on the calendar. Each time you change the day or month or year, the plot of the moon's rise and setting is shown, with the moon phase too.

The other important bits of information shown are:

• Azimuth. As read from a compass, the number of degrees from due north where the moon will rise

• Altitude. The highest point in the sky the moon will reach, due south

• Moon Rise. The time of moon rise.

As you click on various dates the plot gets cluttered; the buttons 'Clear' and 'Draw' do what they say, to redraw the screen with the curent days plot.

14 days later, through the solstice on the 21st, she'll be rising higher and higher each day, rising further north.

Note, all times are BST, and dont take summer time into account.

The colour of the line indicates the visibility of the moon. Black and you can see the moon, yellow and the sun is above the horizon.

For comparison, in 1997, halfway through the 19 year cycle, the moon wanders much less.

Accuracy.

Always a tricky one. The Swiss Ephemeris algorithm is as good as you can get, and it takes into account barometic pressure and temperature effects on the rising and setting times, which will cause changes due to refraction. I've used sea level altitude and 'standard' apparent conditions. The horizon is considered to be at sea level

From the US Naval Observatory the following note is given, and their online calculator gives the same result for moonrise. I'd love to see how it compares in real life!

"Moonrise and Moonset conventionally refer to the times when the upper edge of the disk of the Moon is on the horizon, considered unobstructed relative to the location of interest. Atmospheric conditions are assumed to be average, and the location is in a level region on the Earth's surface. "

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