Iridium Flares

Ernie S.

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Nov 14, 2010
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I have an app for my Android that lets me know when to look and the direction one will appear. There will be a very bright one to my west in a few minutes

From Wiki

Iridium satellite flare
An Iridium satellite

The Iridium communication satellites have a peculiar shape with three polished door-sized antennas, 120° apart and at 40° angles with the main bus. The forward antenna faces the direction the satellite is traveling. Occasionally, an antenna reflects sunlight directly down at Earth, creating a predictable and quickly moving illuminated spot on the surface below of about 10 km diameter. To an observer this looks like a bright flash, or flare in the sky, with a duration of a few seconds.

Ranging up to -8 magnitude (rarely to a brilliant -9.5), some of the flares are so bright that they can be seen in the daytime; but they are most impressive at night. This flashing has caused some annoyance to astronomers, as the flares occasionally disturb observations and can damage sensitive equipment.

When not flaring, the satellites are often visible crossing the night sky at a typical magnitude of 6, similar to a dim star.
 
Another flare here in about 25 minutes. This one will be magnitude -2 or a bit dimmer than venus.
They only last a few seconds and get as bright as magnitude -8 nearing the brightness of the first quarter moon.
 
What instruments are required to view? Binoculars or a telescope?
 
What instruments are required to view? Binoculars or a telescope?

Naked eye, Peach. A telescope or binoculars would limit your field of view and if you did happen to catch one in a relatively large telescope, it might even be painful, like looking ionto the sun.
They are extremely bright, but last only a few seconds. The smart phone app will tell you the compass heading and the azimuth (degrees from the horizon. Most are nearly due East or West of your location and 40 to 75 degrees above the horizon.
My app will alert me roughly 1/2 in advance and I set the kitchen timer to give me a few minutes to get outside and let my eyes get used to the light, then as the flare starts to brighten, the phone vibrates.
The brighter ones, of magnitude -5 or brighter are rather spectacular and if you ever get to see a magnitude -8, you'll swear a motorcycle is bearing down on you. We're talking bright enough to cast a shadow or to be seen in full daylight.
I just find it cool that they can predict with such certainty the when, where and brightness.
If you have relatively dark skies where you live, you may even catch the satellite before and after it flares. It would look like a very dim star that is moving across the sky similar to a high flying aircraft. If you are looking in the right place, you will see it get, like 1000 times brighter in a few seconds and them dim just as quickly.
 
Do you have yours set for ISS?

That is about my favorite using Sattrack.

For other Satellites and rocket bodies and the like, I use the app Satellite AR.

You hold your phone up like with Google Sky, and out shows you the trajectories tracks and locations.

Here's a description....
Satellite AR: Satellite tracking with augmented reality on Android

It's free on android market.

GOTTA get that one! Thanks!

My pleasure, hope you enjoy it as much as I do.
 

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