Jupiter impacts – a field for amateurs?

Professional astronomers have called on the amateur fraternity to begin a close monitoring of Jupiter for impacts by asteroids and comets. Skymania has looked into what is required to do this and how practical it is as an amateur project. We found some mixed views.

Jupiter imaged by Wesley on Aug 30

The suggestion of a Jupiter-watch follows the detection of bright flashes and apparent scars in the giant planet’s clouds by observers with video cameras.

Glenn Orton, of NASA’s Jet Propulsion Laboratory in California, believes such impacts occur more often than was thought.

He was part of a team that investigated a flash from an apparent impact that was recorded on June 3 this year by amateur astronomers Christopher Go in the Philippines and Anthony Wesley in Australia.

The pros turned the Hubble space telescope and giant Keck telescope on Hawaii onto Jupiter to make follow-up observations for a paper accepted for publication in Astrophysical Journal Letters. They deduced that the impacting asteroid was between 8 and 13 meters across and was as powerful as a 250-1,000-kiloton nuclear bomb.

Since they submitted their paper, another bright flash has been observed by two Japanese amateurs, Masayaki Tachikawa and Aoki Kazuo, on August 20. In July last year, Wesley recorded the dark scar that also seems to have been left by an impact.

Orton said: “Jupiter is a big gravitational vacuum cleaner. It is clear now that relatively small objects left over from the formation of the solar system 4.5 billion years ago still hit Jupiter frequently.”

Colleague Professor Imke de Pater, of the astronomy department at the University of California, Berkeley, said: “I bet that if we looked at other data amateurs have, we would see many more events like that.”

Jupiter has long been a favourite target for amateurs who sketch the changing appearance of the clouds, and today some are producing impressive images with video cameras, including webcams.

We asked leading imagers of Jupiter about videoing Jupiter as a project. Anthony Wesley, who has recorded two such events, focused on the actual technique.

He said: “It’s become a lot easier to do this sort of monitoring and photography over the last few years, thanks in equal parts to the improving quality of large aperture scopes (10-inch and over), faster cameras with higher sensitivity, and faster computers to process the resulting videos.

“One thing nobody can control is the quality of the seeing – amateurs are striving to get the highest resolution images of Jupiter that they can, and once you’ve got everything else under control it all comes down to finding good seeing.”

Anthony offered the accompanying recent picture as an example of what can be achieved in good seeing. He said: “This is the sort of thing that is possible to do with amateur-class scopes. In this case I was using a 14.5-inch Newtonian with a 5x powermate for effective focal length of 10m, and a Flea3 high speed video camera. I recorded 3 minutes of video, 1 minute through each of red,green and blue filters, at a data rate of 70fps.

“The high speed video minimises the atmospheric blurring, and afterwards software like Registax will sort through all the frames to find the best ones, align then and average them together to extract the most signal.

“As to how easy or hard this all is… that’s quite subjective. Like all aspects of astronomy it takes some patience and time to understand how to get the most out of your scope, and how to get the most out of the data that you capture. The planetary imaging discipline is quite different to deep-sky imaging, so what you learn in one doesn’t necessarily help you very much in the other.”

Skilled UK imager David Tyler was more cynical about the idea. He said: “One has to decide to spend out £3k to £6k on a good scope, decide what focal length to extend it to to suit the chip and pixel size of the video cam, spend another £4k to 12k on a perfectly aligned mount in a safe, dry, thermally conducive observatory.

“The next stage is learning how to use it and spending every available clear night in freezing temperatures or remotely staring zombiefied at the screen. Nah, it’s not a question of taking up such a project, only an already imaging nutter is mentally qualified. I have thousands of live avi files of Jupiter, Mars, Saturn, the Moon and the Sun and have no intention of sitting and staring at the screen waiting for a flash of fame.

“If it happens, it happens, if I am fortunate enough to be looking at the screen at the time of capture. It’s certainly not for the faint hearted armchair astronomer.”

Fellow British amateur John Dee also warned of the patience needed as well as storage space for the vast amounts of video file data that could build up. But he said software could be adapted to automate the detection of flashes recorded.

He told Skymania.com: “There is already software that will detect meteor strikes. It was first use to detect strikes on the Moon and worked very well recording several impacts. The project would be done by robotic telescope and a computer looking at real-time data from the telescope and CCD detector.

“This project wouldn’t cost very much. All of the hardware would be straight off the shelf. The software would have to be rewritten to accommodate Jupiter’s gaseous atmosphere. So I think this is a very good idea indeed.”

What do you think? We’d be glad to hear readers’ comments.

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