How to use the Almanac: the program opens with the current sky for the central British Isles (54°N, 2.5°W), basing the Universal Time (UT) and calendar date on your computer's clock. The corresponding local date and time, day of the week, latitude, longitude and time zone are also displayed.
Under the selector at top right, you can determine the beginning and end of Astronomical, Nautical and Civil twilight, or the time at which Planets close to the Sun last or first appear.
You may also select an alternative location from the alphabetised pull-down Country and City menus, or enter a new Date (yyyy/mm/dd format) and/or Time (24-hour format hh:mm UT — use GMT in Britain), then click 'Calc' to update the Almanac. You may also step forward or backward in time by one minute, hour, or day by clicking the appropriate button. Clicking 'Reset' restores the program to the current date and time.
Crucial note: only select the Daylight Savings Time? button if appropriate for your chosen location and season!
International Space Station: select the Add ISS passes? button if you wish to display predictions of the space station's visibility for your chosen location over the next five days. It is computationally intensive, slowing the program if not required.
Jovian data: select the Add phenomena of Jupiter? button if you wish to display Great Red Spot predictions and details of eclipses, transits, occultations and shadow transits for Io, Europa, Ganymede and Callisto. As with the ISS predictions, selecting this option will slow the program if not required.