INSTRUCTIONS FOR NOCTURNAL
The Nocturnal is a star-clock which was invented over 500 years ago to determine the time at night using bright stars. The original instrument worked in the Northern Hemisphere using the pole star Polaris for reference and Kochab for the hour angle. However, the original design could not be used in the Southern Hemisphere as there was no corresponding bright star at the South Celestial Pole. In 2023, Tony Sprent in Tasmania developed a new design using Alpha and Beta Centauri and the Southern Cross for use in the Southern Hemisphere.
WHERE TO HOLD INSTRUMENT
Hold the instrument on the small handle vertically and downward - which is part of the outer disk featuring the months and date scale.
HOW TO FIND POLARIS
You can find Polaris within the Little Dipper asterism, formed by the brightest stars of Ursa Minor. Just find the Big Dipper. The two stars on the end of the Dipper’s “cup” point the way to Polaris, which is the tip of the handle of the Little Dipper.
HOW TO FIND THE SOUTH CELESTIAL POLE
There is no bright star at the celestial pole in the Southern Hemisphere. However, it is possible to find the South direction using the Southern Cross and the Pointers (Alpha and Beta Centauri) as shown in the diagram.
NORTHERN HEMISPHERE NOCTURNAL
1 - Find the Pole Star which is part of the Ursa Minor constellation and face North. Note: Please refer to the previous section to find Polaris
2 - Hold the instrument using the small handle (A) marked N- which is part of the outer disk (B) featuring the month and date scale.
3 - Align the pointer (C), part of the inner disk (D) and decorated with a moon face, with the corresponding date on the outside disk (B).
4 - Now sight Polaris through the centre hole (E) of the instrument with the handle in the downward direction. You will need to tilt the instrument up so that you can clearly see Polaris through the hole, making sure the handle remains downward. If you know your latitude, that will be the angle you have to tilt it up.
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SOUTHERN HEMISPHERE NOCTURNAL
1 - Find the Southern Cross and Pointers to locate and face your South direction.
2 - Hold the instrument using the small handle (A) marked S - which is part of the outer disk (B) featuring the month and date scale.
3 - Align the pointer (C) decorated with a moon face, on the inner disk (D), with the corresponding date on the outside disk (B).
4 - Still facing South, hold the instrument with the handle pointing downward, and tilt it up until the central hole (F) is aligned with the celestial pole (as estimated using the Southern Cross and Pointers):
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