I missed another Iridium Flare..how long do they last?
Hi guys,
After catching my first -1 flare last week, I tried last night around 6:20pm for a -8. My wife left work early so she would be home in time and I invited one of the neighbours over for a look as their son is very interested in science.
We were all staring into the sky by about 6:20 (prediction was 6:23:40) and looked in what I thought would be the correct place...at about 6:26 we gave up! Our daughter reckons she saw something but it only lasted a very brief period.
So my question now is, how long do they last? The one last week lasted nearly a minute as it traversed across the sky. Do they all last this long or do they vary a lot, down to litterally a "flash"?
I've seen dozens now - never seen one last a minute though? From an urban area, from starting to see them to gone takes about 10sec....
In really dark areas you can sometimes see them coming before they flare - but they are really dim before they flare.
Did you see an iridium or a satellite? Just seems very long....
I tried to find my photo with a -8 flare but for some reason it's vanished (or not where I expect to find it) but I found another one. I think it might be a -3 or -4 from memory.
I've seen dozens now - never seen one last a minute though? ...
I thought it was long too, but it was heading in the right direction (just off due north) and the right brightness (-1, I compared it to Alpha Centauri and they were pretty close in birghtness). Maybe not a minute, but certainly 20 seconds or more.
The next one I will try to not be distracted by trying to set up a video and direct other people where to look.
You probably saw a bright satellite (ISS etc) - an iridium doesn't hold the same brightness - it rapidly brightens (the flare) then just as rapidly fades, over less than 10sec or so.
If you have astro software - check the alt/az info for your loc at that time, and that will give you a very good indication of where it will flare - ie, in between the moon and arcturus..... really helps, especially with the less bright flares.
So my question now is, how long do they last? The one last week lasted nearly a minute as it traversed across the sky. Do they all last this long or do they vary a lot, down to litterally a "flash"?
A few seconds. You might find www.heavens-above.com very useful as it has a highly accurate online calculator for Iridium flares. Knowing your exact location (GPS) will really help as the flare brightness drops off rapidly and being a couple of Km of the track results in a couple of magntude brightness difference.
I've only seen a couple, I saw a great -8 at just after dusk a few months ago. I could see it before the flash travelling slowly across the sky like other satellites I've seen, then brightened up until it was brilliant and then dimmed over just a few seconds, maybe 5 - 10 seconds or so, then I could see it for another several seconds.
I 'think' the best ones are just after dusk/sun down, I can picture it in my head but it may be hard to describe: What you are seeing is the reflection of the sun off the satellite, so just after dusk satellites have the most time before they traverse into the earth's shadow.
Hi here is a mag 6 flare taken last month close to Saturn and the Beehive cluster (M44) early in the evening. Minolta SRT101 55 mm lens 800 iso piggyback on Sct,the shutter was open for about 1 minute.
Replies so far have pretty well covered your original post but I thought I would add my 2 cents anyway.
Provided you have configured your location correctly, the Heavens-Above web site predictions will be spot on.
There was a -8 pass over Newcastle last night and even though I was at work in an industrial area heavily polluted with artificial lighting it was brilliant!
Providing you are looking in the right area at the right time your eye will be drawn to the flare.
Damn - didn't know that one was coming - should check heavens above more often.
I usually keep the iridium and ISS pass info on the fridge!
One of the few good points about doing 12 hr night shifts (6:30pm - 6:30am), you get to see most of the night sky, albeit through terrible light pollution.
I like to check the weeks predictions before commencing my night shifts (when I remember). Just got lucky this time I guess.
I also get a kick out of seeing the "WOW" factor on the faces of my work colleagues when I show them one of the brighter Iridium flares.
Just observed an awesome flashing Satellite, UFO 2 Rocket1. If you like Iridium's you will love this one. It was moving very fast I'd say twice the observed speed of the ISS, it flashed to mag -2 or -3 about 5 or 6 times from horizon to horizon. Highest Alt of the pass was 79 deg, time 18:33.
