Occultation of Saturn, Tuesday, 17 September 2024, Northern Australia.

The eastern sky at 19:26 AEST Tuesday, September 17 as seen from Brisbane (almost 60 minutes after sunset) with Saturn just about to be occulted by the Moon. The inset shows the telescopic view at the time. (click to embiggen).	The eastern sky at 18:33 ACST Tuesday, September 17 as seen from Darwin with Saturn just exiting the Moon as the occultation ends. The inset shows the telescopic view at the time. (click to embiggen).	The eastern sky at 19:08 ACST Tuesday, September 17 as seen from Cairns with Saturn just exiting the Moon as the occultation ends. The inset shows the telescopic view at the time. (click to embiggen).

On the early evening of Tuesday, 17 September, between 6pm and 7pm  there is an occultation of Saturn as seen from Northern Australia (Queensland and Central Australia). Everywhere else sees a graze or close approach. This is the third and final of three occultations seen from Australia this year. This best as a binocular and telescope event. The Moon will have just risen in some areas, so ingress may be difficult for telescopes, although Saturn’s exit may be a lot easier.

The path of the occultation, taken from the IOTA site 

This occultation is visible from the eastern and central Australia from the latitude of Surfers paradise and up (see table below). Other sites at the same approximate latitude will see similar views.

In the rest of Australia the Moon and Saturn will be very close when the Moon rises (eg Coffs Harbour sees a graze).  

Start watching about half an hour beforehand to get set up and familiar with the sky. Saturn will disappear behind the dark limb of the Moon very close to the horizon. In Alice Springs and Darwin the Moon will rise with Saturn behind the Moon. Generally, you will need a level, unobscured horizon to see the occultation at its best. 

Again, as the Moon is close to the horizon when ingress occurs (15-20°) it may be difficult to get telescopes to point that low, and binoculars may be required. By the time Saturn reappears the Moon will be higher (around 26°) so telescopes will be successful. 

Imaging Saturn and the Moon together will be a challenge, due to the differences in brightness, especially as the Moon is nearly full and the dark limb is a thin sliver. You will need a high ISO (3200 to 1600) to have a short enough exposure time to stop Saturn from trailing, but the Moon will be over exposed , you may need to take short exposures of the Moon and  long exposures of Saturn and overlay them. 

Try practicing the night before to get an idea of your cameras/mobile phones performance. You will need a tripod for your camera or binoculars, and possibly some way to attach the camera to binoculars or telescope (dedicated amateur astronomers will already have this kit). See this post for some examples.

More cities in Australia and elsewhere can be found at the IOTA site (UT times only).