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Old 01-09-2016, 10:24 PM
poider (Peter)
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Not the ISS and not a Meteor??

Tonight 01/09/2016 at approximately 7:15pm I was outside trying to set up my telescope for some astro photography (I am about 25 klms south of Adelaide) when a saw a light slowly make it's way from the south east toward the north west, I have watched the space station and have seen many meteors but this was different, It was probably twice as bright as the ISS and heading in the opposite direction, it started near the Southern cross and was quite bright until it got close to scorpius then it dimmed for a bit then was gone, It didn't fade out of view and when it changed magnitude it wasn't gradual it just went from being bright to being dim and when it vanished from my view it was just as though the light was turned off, does any body know what this may have been
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Old 01-09-2016, 10:30 PM
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Stonius (Markus)
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Iridium Flare?
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Old 01-09-2016, 10:38 PM
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Iridium Flare?
That would be my vote too.
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Old 01-09-2016, 10:42 PM
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What actually is an Iridium Flare??
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Old 01-09-2016, 10:52 PM
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Basically a tumbling satellite. As it rotates (spins) it can reflect sunlight down to the Earth usually off of the solar panels.
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Old 01-09-2016, 11:10 PM
iasuka (Dmitry)
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Iridium satellites are the 60+ satellites of Iridium sat-based telco system. According to http://www.heavens-above.com/IridiumFlares.aspx there were no flares predicted for Adelaide for today. Based on that I'd say the described event is unlikely to be an Iridium Flare.

Of course, there are lots of other satellites in low orbits so similar although less brigth flares can probably be seen every day.
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Old 01-09-2016, 11:39 PM
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The only one I could see that was close was the last one in the screencap. For McLaren Vale (which, I guess is around 25km south from adelaide) there was a flare that was Mag 0.1, and brighter if the original OP was west of that point. It would have appeared in the SSW at 6:56pm. It's been a while since I observed Iridium flares - I assume the 50 Degrees is the point of greatest magnitude?
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Old 02-09-2016, 05:01 AM
poider (Peter)
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Yes i checked heavens above and there was a flare at 6.56pm
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Old 02-09-2016, 07:40 AM
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Quote:
Originally Posted by Atmos View Post
Basically a tumbling satellite. As it rotates (spins) it can reflect sunlight down to the Earth usually off of the solar panels.
I believe that the Iridium sats are not tumbling, its just the reflective solar panels that happen to shine onto a certain location, I could be wrong but if it was spinning it would have a variable brightness that is unpredictable. I caught a tumbling sat once in an exposure of m42 as seen http://i.imgur.com/S0wJRYS.jpg here, it makes 3 different reflections.


Dan
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Old 02-09-2016, 09:32 AM
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If it was bright for some time it would not normally be an iridium satellite,they are just normal satellites that flair at a certain point then fade back to normal brightness.
The brightness of the iridium flair is only at the best a few seconds, so for the satellite to be brighter than the ISS for any length would be an anomaly?
As for cutting out sharply it has just gone into the earths shadow.
If you follow satellites in binoculars they can be seen long after you can see them with the unaided eye.
How long was it bright for,and was the brightness constant untill the fade out.
There are thousands of satellites out there,but none brighter than the ISS which can reach -8.5-9.0 magnitude.
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Old 02-09-2016, 09:43 AM
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There are thousands of satellites out there,but none brighter than the ISS which can reach -8.5-9.0 magnitude.
Cheers
The ISS has a max magnitude of -5.9, and iridium flares can reach a maximum of -9.5 https://en.wikipedia.org/wiki/Apparent_magnitude. I think this is because Iridium sats reflect the sun like a mirror, and thus will only flair for a small area on the ground, however the ISS just reflects light normally with no flairs. Like shining you watch in somones eye vs trying to shine you arm in someones eye, the watch will be brighter because of the reflection, whereas the arm is more diffuse.

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Old 02-09-2016, 10:06 AM
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Originally Posted by Stonius View Post
The only one I could see that was close was the last one in the screencap. For McLaren Vale (which, I guess is around 25km south from adelaide) there was a flare that was Mag 0.1, and brighter if the original OP was west of that point. It would have appeared in the SSW at 6:56pm. It's been a while since I observed Iridium flares - I assume the 50 Degrees is the point of greatest magnitude?

Iridium 19 was traveling from the tail of Scorpius to central Octans

Opposite direction from the OP comments.
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Old 02-09-2016, 11:28 AM
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Iridium 19 was traveling from the tail of Scorpius to central Octans

Opposite direction from the OP comments.
Ah, true - I didn't click through to the chart!

The mystery remains...
:-)

Markus
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Old 02-09-2016, 01:09 PM
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Originally Posted by Windston View Post
The ISS has a max magnitude of -5.9, and iridium flares can reach a maximum of -9.5 https://en.wikipedia.org/wiki/Apparent_magnitude. I think this is because Iridium sats reflect the sun like a mirror, and thus will only flair for a small area on the ground, however the ISS just reflects light normally with no flairs. Like shining you watch in somones eye vs trying to shine you arm in someones eye, the watch will be brighter because of the reflection, whereas the arm is more diffuse.

Cheers
Dan
To contradict you, the ISS can flair, I have observed on a number of times
I may not be as dramatic as an iridium flair but flair it can
Cheers
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Old 02-09-2016, 04:43 PM
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Watched a very bright, slow mover on Aug 31. Was travelling west to east, and was very bright until approx north east in relative direction. Can't remember time, but it was fascinating to watch none the less.
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Old 02-09-2016, 10:47 PM
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We need to be clear on timing... OP stated 01SEP Local time...
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Old 03-09-2016, 12:02 AM
poider (Peter)
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How long was it bright for,and was the brightness constant untill the fade out.
Cheers
It was bright for about 7 seconds then seemed to be half as bright for as long I watched it in binoculars for a few seconds then lost it when i tried naked eye
Peter
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