Another what did I see question!

[Dibbadobba]

Hey Guys,

I was just looking at the sky, looking north of the southern cross, and noticed a flash, it didn't move and happened very quick just like a star turned on and straight off. I thought it was just my eyes playing a trick on me. But then as I was looking in the area just a few moments later it happened again!

I've heard about the iridium flares or satellites or whatever they are, TBH I have no idea what they are so could that be it?

I went inside and grabbed my bino's to see if I could spot any satellite but couldn't see anything moving.

Any ideas?

[Blue Skies]

Sounds like a tumbling satellite to me. They can be like that - the quick flash, then nothing for a few seconds, then a flash again, seemingly in the same spot. If you can get some optical aid on them you can see that they have a series of flashes as they tumble but most of them aren't very bright. And they do move, just very slowly. It's very easy to be tricked to thinking its stationary, your eyes/brain are actually pretty bad at judging slow movements.

[Dibbadobba]

Thanks for the explanation, That would make sense, to be honest it took a while to take in what it was I didn't really notice if it moved or was in the same spot, but generally the same are. Seeing conditions don't seem the best everything is twinkling so at first I thought that May have been the cause, but when it happened a second time I knew it must have been something floating around. I find it amazing the things we are able to see from earth! Is a tumbling satellite a functional one or just one literally tumbling uncontrollably?

[Blue Skies]

It's functional, I think its for stability. They're spinning, really. Not sure why we tend to call them "tumbling." Perhaps someone else can help with that.

[Rob_K]

Satellites can do lots of funny things! :) The other night I picked up a series of bright 'stars' in my subs. While there was no satellite trace showing (too dim), the apparent movement of the 'stars' was entirely consistent with them being flares off a geosynchronous satellite. The area was about 7-deg off the Celestial Equator.

Because there is no trailing, the flares must have been no more than a second or two in duration, essentially flashes. If you were observing from the ground you would have seen a bright naked-eye flash (I missed it, bloody cameras!), followed a minute or so later by another in the same apparent position, etc (but there appears to be irregularity in the timing of the flashes). Here's an animation - each of the 4 consecutive subs was 75 sec in duration, followed by 75 sec ICNR, and three of the 4 subs picked up a flash. Zoom was 200mm and the naked-eye would pick up no apparent movement between the satellite & the starfield across the exposure time:
http://i727.photobucket.com/albums/ww271/Rob_Kau/Satelliteanimation24Sept201312-25to12-34UT.gif

By contrast, here's another flaring geosynchronous satellite I picked up on 10 Aug 2013 (presented at wider scale than previous animation). This time there are trails. Exposure time was 60 sec for each sub so the flare lasted around a minute. It may have been naked-eye, hard to tell - probably not terribly bright. If you were looking skywards in the right spot, you may have seen a star appear and then disappear around a minute later, with no apparent movement.
http://i727.photobucket.com/albums/ww271/Rob_Kau/Satelliteflare10Aug2013textanimatio n.gif

Cheers -