Thursday, November 12, 2009

Leonid Meteor Shower , Wedensday November 18 2009

The north-eastern horizon in Australia at 4:00 am AEDST on November 18, the Leonid radiant is marked with a cross.

The Leonid meteors may be of interest this year. The Moon is just after new, so there will be no Moonlight interference with this shower, and there are a number of predicted peaks in meteor activity.

The biggest peak will occur sometime between 21 hr UT and 22 hr UT onNovember the 17th. Sadly, that's 8-9 am AEDST, well after sunrise. Unlike the Orionids for example, the Leonid peak is rather sharp, so we will only catch a bit of the upward swing, although people in Western Australia will have the best chance of seeing part of the peak. People in South East Asia should be treated to a higher than average number of meteors. How many meteors? Well, predictions of Zenithal Hourly Rates range from 140 meteors/hour to 300 meteors per hour, with the best predictions being around 200 meteors/hour (a high of 500 meteors/hour has been revised downward). There is also a couple of minor peaks that occur before Leo rises in Australia and South East Asia.

The best time to observe in Australia is the morning of the 18th between 3 and 4 am (daylight saving time, 2-3 am non-daylight saving time). When you get up, allow at least 5 minutes for your eyes to adjust, and be patient, it may be several minutes before you are rewarded with you first meteor, then a couple will come along in quick succession. Choose a viewing spot where you can see a large swathe of sky without trees or buildings getting in the way, or with streetlights getting in your eyes. The darker the spot the better (but do be sensible, don't choose a spot in an unsalubrious park for example). A lawn chair or something similar will make your observing confortable (or a picnic rug spread on the ground and a nice pillow), and having a thermous of hot coffe, tea or choclate to swig while watching will increase your comfort. (Here's some hints on dark adaption of your eyes so you can see meteors better).

So how many meteors will Australians see? Well, maybe as few as one every 10 minutes, or maybe one every minute, depending in the background rate between the main peaks. one every 5 minutes is more probable, with the best viewing in the countryside.

Nonetheless, the possibility of seeing a quite reasonable number of meteors is good, and the meteor peak may come early (and people in Western Australia will have the best chances of seeing good meteor activity). There is also a small peak around 2 am on the morning of the 19th that may be worth watching for, despite Leo being low on the horizon.

The Radiant (where the meteors appear to come from) is in the Sickle of Leo. Even if there are only a few meteors Orion and the Hyades will be visible and bright Mars will be nearby, not far from the Beehive cluster. So it will be a quite nice morning, and well worth getting up for on the off chance there will be some decent meteor numbers, although the meteor flux estimator says our rates will be rubbish (don't forget to change the date to 2009). Cloud cover predictions can be found at SkippySky.

UPDATE: My report and links to other observations is here.


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