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Hunt for Iridium flares???


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We look for geocaches and benchmarks, why not Iridium flares? The neat thing about this is that on just about any clear night you can see one. The challenge is using your GPS to get you to the right location to log that Iridium flare.


What is an Iridium flare? They are dazzlingly bright flares from Iridium satellites as they pass over head in the morning just before the sun comes up or evening just after sunset. The flare is really a reflection of the sun off of the huge mirror like antennas on the satellite. I’ve seen about a dozen over the past few years and they are very very bright! It last for about 6 of 7 seconds and are just a trip to see if you have never seen one.


What’s the rub? Well, this reflection is only on a very small area (or footprint as they say in satellite terms) on the earth surface. You are going to need your GPS to get you in the center of this footprint. Second, timing is everything here. You are going to keep a very close eye on your GPS clock. Your GPS clock is vary accurate, it get it’s timing from the GPS satellites, which is why you didn’t have to set it.


Try entering in your coordinates at this URL:




Along with giving you the time and date of the Iridium flares over the next 7 days, it will also tell you which Iridium satellites will produce the flare for those coordinates.


So why not make a special section for Iridium flares? Just like we have a special page for each cache, let’s have one for each Iridium satellite. When you see an Iridium flare, log the sighting under the page for that satellite.


So, I propose that for a change of pace, that we look up rather than down. Any comments?

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I love this idea! I've been a bit of an astro-nerd for a few years now, and you're right, the iridium flares are quite spectacular...


That being said, off we go to the nether reaches of possible implementation......


The path for a particular iridium flare can be several miles wide depending on the minimum acceptable mangnitude limit you set in order to qualify for a "hit" or find. For the greatest magnitude - you're right - you'd need to be in (or very near) the center of the track, otherwise you may still see the flare, but not at the greatest magnitude possible!


However, I wonder how we could standardize/confirm the observations to allow logging of a hit/find.....


Subjective observaton can vary significantly, so perhaps a magnitude limit wouldn't be the best criteria.... Maybe a link with Heavens Above to confirm the observational data... If you enter these coordinates and this time it could show a find (or not) as appropriate?


Based on that, HA provides an estimated magnitude based on the location you enter.... Maybe that's how we qualify the finds.... Must be mag -4 or better to qualify based on the location and time you enter.


That would give you a generalized location down to a couple of square miles I would guess and would be possible to implement.....


Interesting idea!


Good luck!





I just need a fix!

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Wow . . this thread has been open for almost 3 hours and NOT ONE Markwell yet?!?!?! I guess it's up to me icon_wink.gif


Iridium Flares were discussed way back HERE. I've been looking forward to the opportunity to spot one, but just haven't been able to take the time yet. Maybe now that summer's coming I'll be able to.


Thanks for the reminder!




"The kingdom of heaven is like treasure hidden in a field.

When a man found it, he hid it again." Mt. 13:44

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So - Bret


I take it you didn't get a chance to catch one at the time of the other thread? (Of course, in November it was probably just too doggone cold!)


There's usually 3-7 per week of varying magnitudes near my house...


And then there's all the other sorts of stuff that's floating around up there - rocket boosters and all sorts of junk - that you can sometimes see...


Fun stuff!


Thanks for the linkage!





I just need a fix!

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Originally posted by oicu812:

We look for geocaches and benchmarks, why not Iridium flares? The neat thing about this is that on just about any clear night you can see one. The challenge is using your GPS to get you to the right location to log that Iridium flare.


I had been looking at the heavens above site for a long time to find the "perfect" flare to show my family.

We did it last fall and to make Dad look like a deity just have him point to the darkened sky and say, "in fifteen seconds the heavens will flare there". (Do a Heston like Moses).

Cool site. Cool use of a GPS to find the brightest magnitude of the flare.

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A possible explanation of your Iridium flare failure could be that the Iridium satellite, that was to produce the flare, is tumbling in its orbit. I do know that a handful of the Iridium satellites have started to tumble in their orbit and have had to be replaced with newer satellites. A tumbling satellite will not produce a flare at the predictive time. It can sometimes produce a flashing flare but that’s about impossible to predict.


One additional note to people using www.heavens-above.com, please pay close attention to the format requirements of the coordinates. I think most people here on this forum understand that, I’m just stating this to the casual observer who may not be aware of the different formats of LON/LAT.

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Wow.... I had forgotten about Iridium Flares. Ham Radio Satellite Operators have been watching these for a number of years now. I did it too, till it got boring. It is a neat thing for a few times, then... seen one flair, seen em all. icon_biggrin.gif


Mike. Desert_Warrior (aka KD9KC).

El Paso, Texas.


Citizens of this land may own guns. Not to threaten their neighbors, but to ensure themselves of liberty and freedom.


They are not assault weapons anymore... they are HOMELAND DEFENSE WEAPONS!

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