Tuesday, November 17, 2009

The Null Experiment: Taking Leonid Pictures

First off; I tried to take meteor pictures and got no results, i.e. a null experiment. But it was an interesting exercise that I thought I'd share.

I have a long history of spending time out at night watching for meteor streaks in the sky, and have many good memories of those times. When I heard that this year's Leonid meteor shower was going to be a dark sky with no moon and with the sky washed clean by the passing of a cold front the day before, I knew I would have a chance even if the projected rates weren't very high.

I also knew what that 20 per hour rate quoted on the internet for North America viewers actually meant. If you had eyes on the back of your head and never blinked while watching from the top of Pikes's Peak, you might see 20 per hour. I also knew I hadn't prepared my sleep cycle for this and knew I couldn't stay up and watch the whole night.

But, maybe I could take a picture. I already had all the pieces. My original iPhone (the one that went into the pool) was in reasonably good shape and I had the TimeLapse app for automatically taking a series of photos. I dug out the old iPhone and charged it up.

From previous experiments of night time photography I knew the chances were slim, but I'm always willing to try something like this. I propped the iPhone up on the table out on the rear deck and set the TimeLapse to take 9999 photos back to back. I started it about midnight and warned Mary Ann not to be disturbed if she saw an iPhone glowing softly in the dark. I set it for Dark Display but even then it glowed.

Best case, I hoped that a large fireball would streak across the field of view during a photo, bright enough to be visible. I knew I was likely to see only the brightest of stars, and those just barely.

After doing some old-school staring at the sky, plus some lounging in the hot tub trying to peer through tree branches, I gave up and went to bed, only seeing one faint streak and one bright one that I couldn't turn my head fast enough to see full on.

For some reason, I woke back up at five and went to check the iPhone. The old battery had lasted for two and a half hours, taking 1031 pictures of the black sky. I copied them off using Image Capture and then peered at the results. Tweaking the brightness and contrast of one photo left me sure that I'd get nothing. The sensor noise was indeed almost as 'bright' as the stars. Using Quicktime Player 7 (it's an optional Snow Leopard install) allowed me to open the whole set of 1031 jpegs and play them like a movie. Playing with the A/V controls to get better brightness and contrast left me with a slow creep of stars across the sky. There were more stars than I'd seen just staring at one image, but this was hardly YouTube material.

And there were no visible streaks on any of the 1031 frames. It was a bust. There might have been something, but it would take a lot more image processing than I was willing to spend trying to get anything useful out of all the sensor noise. (You are welcome to try. Click the black image to get to the full size photo and have fun with Photoshop. There are two or three stars you should be able to see.)

But I learned that this process was a handy way to get a time lapse movie, hopefully in the daylight. And at about 5:30 in the morning I saw a rather nice Leonid streak by, using the old school method of staring at the sky in the cold.

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