Sunday, March 11, 2012

Iridium Flare Observation 2012-03-11

I like watching satellites, especially the big ones like the International Space Station (ISS). Other amateurs frequently report of seeing an Iridium flare. An Iridium flare is a bright reflection of sunlight from any one of a series of communication satellites from Iridium Communications Inc. with bright reflective panels that acts like mirrors in space (or outside earth's atmosphere).  Even with convenient websites like Calsky that reports of daily satellite prediction I still haven't seen one of them. I just didn't bother observing them. I suspect that I might seen at least one, but I didn't know that it was an Iridium. The break came when a fellow astro enthusiast reported several bright Iridium flare predictions on March. When I read his post, It was already 7:35 in the evening only 5 minutes away from the predicted time. I didn't immediately went outside to observe. I thought setup will be easy since I only need a camera on a tripod. I waited a bit, check some emails before going up. I thought I still have some time to setup, but I was wrong. The moment I stepped outside, I saw a point of light as bright as Venus or even brighter at the predicted location NNE. I knew I was too late, my clock must be off or the predicted time is off. After a few seconds, the bright point of light faded. I didn't try to observe again, because I'm pretty sure that was it. Even though I miss the shot, I'm still glad I saw my first Iridium flare.

The following day, I tried setting up my camera on a tripod outside 15 minutes earlier than predicted time. This is a -8 magnitude flare, much brighter than Venus and I don't want to miss a good opportunity this time. I fired a few test shots to calibrate my exposure settings. Then I waited for the predicted time of 7:34 pm. When I saw a dim point moving, I immediately started my 15 seconds exposure. I was completely focused on that point and my camera that I missed the actual flare. When I checked my exposure, there were actually 2 satellites. The one I saw was not the Iridium 40. It was fortunate that I captured the satellites. It's like hitting 2 birds with 1 stone.

The dimmer satellite trail can be seen to the left of the flare from Iridium 40.

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