CN FORUMS ARCHIVE Telescope Reviews: Iridium Flares

I've been on this kick to try to photograph some Iridium flares. It's a real bear out here, because we have so much light pollution that holding the shutter open for four seconds is enough to make it look darn near daylight.

Last night, I was bound and determined to catch one. There were two passes, both towards the north and both low, but one was going to be pretty bright. They were about an hour or so apart, the brighter being earlier and just at dusk. The sky was going to be relatively bright, but the intensity of the flare was going to make up for it.

I set up 30 minutes early. That was always my biggest mistake. I would wait until just a few minutes before the flare, and then be caught while I was still focusing or framing the area. Not this time!

I was focused, the area was framed. Wide angle, 18mm so even if I was off on where it was going to be, I would still catch it. I would go for ISO100 and hold the shutter open for about 4 seconds. I took a few test shots and got pretty excited. At that ISO with 4 seconds of exposure with the lense set at f/22, I could just see a little blue of the failing dusk and a lazy cloud or two glowing a deep crimson. If I could catch this flare, it was going to be a gorgeous shot.

Then I started to out think myself. What if the flare is too dim to show up properly with these settings? Maybe I should speed the film up a notch, or increase the exposure. I played around a bit more, and settled on what I had before.

I looked at my watch. Uh oh! Flare is in 20 seconds! I started taking exposures, one after the other. The buffer was full, and it started dumping to the card. No, just a few more exposures! Hurry, hurry! I took another two, and the camera struggled to keep up. This time, it wasn't letting me take another.

I missed the flare. It was beautiful, but I missed it!

Did I catch the next, dimmer one? Of course I couldn't be so daft as to screw it up again? Well, I did. I missed both flares.

Tonight, however, was going to be different. The center of the flare was practically on top of me. A cool magnitude -7, with an altitude of 23 degrees and azimuth of 14 degrees. Almost exactly where the last two were. Iridium 39. This was the one I would finally catch.

Once again, I set up early. When I was satisfied with the exposure settings, I looked at my watch. It just hit 19:37, so only one minute and 26 seconds to flare. The plan was, I would start counting down as soon as the watch, carefully synchronized to the atomic clock, hit 19:38 and open the shutter at the very first sign of the flare. Usually, they start very faint and then quickly grow in brightness. The clock hit 19:38 and I looked up. *bleep*! It started early!

I immediately hit the shutter, and hoped for the best. And now, ladies and gentlemen, is the first in focus Iridium flare I've managed to--just barely--catch. It is my great pleasure to introduce to you, the slightly early Feb 28th flare of Iridium 39 over Las Vegas, Nevada.

http://home.hiwaay.net/~caver/iridium39.jpg

The tall beam of light is the Luxor light. I could have adjusted the levels a little lower, but I didn't want to remove the beam completely. If you didn't spot it, Iridium 39 is in the upper left corner.

I learned a few things tonight, not the least of which is to not fuss--just get the darn shot! One thing is, timing is everything, and it is apparently pretty tough to get these timed to the nearest few seconds. Second, is that four seconds is a very long time, but not long enough to catch the entire flare, so I should expect at least 15 seconds of exposure.

All that means that if I am going to catch a full flare, I will definitely need to go to a dark place and do a full 30 second exposure. Better still, just hit the shutter 30 seconds before the flare is due, and release it after it is done. But I need a darker site for this!

If anyone has any tips, or any good shots of Iridium flares, please let me know!

-Caver