French Meteor Observing Network -

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Observing campaign : Orionids 2007

French version

Related to the famous comet 1P/Halley, the 2007 Orionids will benefit of a perfect observing sky: one more reason to monitor this shower which surprised astronomers last year.

Actuelly, one year ago, Orionids enjoyed all observers who were out during the nights around October, 20th: instead of the usual hourly rates of 20 orionids, ZHRs raised and reached to 60! A rare activity outburst from this shower which is more famous for its regularity...

Regularity which should be back again, this year, except if we are exceptionnally lucky! Anyway, even with only 20 meteors per hour, this shower offer enough spectacle not to get borried during the second part of the nights around October, 20th. Moreover, the Moon will set around 0h Ut at this time, exactly when the radiant rises, which creates ideal observing conditions. For those who can't observe more than one hour per night, it is thus recommended to observe the hour before astronomical dawn (thus between 3h 30 and 4h 30 UT, or maybe, between 4h and 5h UT), when the radiant is higher in the sky, and the Orionids more numerous!

The maximum is predicted to occur this year around 21h UT, on October, 21st, whiwh doesn't favor European countries, as the radiant will be set at that time. But Orionids are full of surprises, which should allow us to benefit from them! First, the shower is relatively complex, and its radiant seems to be composed of several sub-radiants which make the activity quite comfortable severl dayx before and after the "official" maximum. Thus, around October 17th-18th, a first maximum could occur, because it has ever been observed in the past. And between this date and October 22nd, activity should be above 10 Orionids per hour, which is an interesting rate when you just observe meteors! And the nights preceding and following the maximum, activity should be closed to its maximum, as the peak is not very sharp.

Orionids often produce bright meteors, and it's possible to try to photography some of them. The video can also be usefull for that stream. As usual, radio/radar observations are should absolutely be conducted if we want to cover as completely as possible the activity of the shower: it's the only way to monitor the orionids after the Sun rised. Eventually, visual observations will be always so interesting, for their scientific aspect as well as their esthetic one! To as much 1P/Halley dust as possible, you should direct your eyes in the direction of the Lynx. And if the Eastern horizon is dark enough, you can also observe close to Cassiopea.

Orionids are very swift: with an atmospheric reentry of 66 km/s, they are one of the fastest meteors, close to the speed of Leonids and Perseids. That should be a characteristic which will help to recognize them from most of the other meteors. But that won't be enough to differentiate them from the very close epsilon-Geminids (atmospheric reentry speed : 70 km/s), which are active at the same period. To distinguish them, you'd better observe in Perseus region: like that, epsilon-Geminids and Orionids won't have the same trajectories, and it will be easier t separate the two sources using their paths.

Clear skies to all!

And don't forget to let us know about your results!


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