odd sighting

I was outside tonight, and saw something I'd never seen before. It was certainly a satellite- right speed, right track- but its magnitude oscillated from nothing to fairly bright (about on par with Altair) on a 15 second cycle.

Anyone else ever seen this? It was very cool, and I'm sure anyone who didn't watch the sky regularly might mistake it for an *cough* import or tourist. I'm assuming the satellite is spinning and the changing faces have different reflectivity, but I didn't think most satellites continued to spine after the solar panels and other squashed down bits had been pulled out by centripetal force if that was the method they used.

Thanks to your post, I learned something.

An excerpt from heavens-above.com:

"Quite a number of satellites that can be observed are tumbling, and this causes their brightness to vary with time. This variation can often be seen with the naked eye, and the frequency of the brightness peaks can range between several per second, to once every minute or so...The tumbling can be started by several mechanisms, but the most common is probably out-gasing."

The full text is here.

Hi Ironraven,

Sounds to me like you witnessed an Iridium Flash.

http://www.assa.org.au/observing/iridium/

I once saw an iridium flash over east Scotland during the daytime. The locations and times of the Iridium flashes can be predicted and observed in advance.

I did see a small satelite come down the other night. It came from the southwest and fell to the northeast. It did not take long to burn up, once it had heated up.

Great info. Now I know what those stationary lights are. I kept thinking they're too bright and in the wrong place to be a star. Is there some sort of sky guide to these satellites?

Heavens Above

"Our aim is to provide you with all the information you need to observe satellites such as the International Space Station and the Space Shuttle, spectacular events such as the dazzlingly bright flares from Iridium satellites as well as a wealth of other spaceflight and astronomical information.

We not only provide the times of visibility, but also detailed star charts showing the satellite's track through the heavens. All our pages, including the graphics, are generated in real-time and customized for your location and time zone."

LED,
If they're stationary, those might not be satellites you're seeing. A satellite is buzzing across the night sky at a good clip (17,500mph if I'm not mistaken), and can usually only be seen from about the 10:00 and 2:00 positions. After that, it it's so far away and moving so fast that it begins to fade and disappear from (naked eye) vision.

Ironraven,
I've never seen what you described unless I did and didn't take note of it... maybe just dismissed it. I'll have to watch for that effect.

If anyone has access to quality night vision devices, take a look at the night sky on a clear, dark night. I was amazed at how many satellites are moving up there. It made me feel ignorant. Also, they're travelling in all directions, as opposed to the normal north/south direction that we see most of them travelling.

Stationary... The only things in the night sky that appears stationary is Polaris. If you mean stationary relative to known stars, if it is twinkling, it is a star. If doesn't twinkle, it's a planet. If it's noisy and blinking, you are a landing strip and about to become road kill.

This guy moved as a satellite. I'm tempted to say it was an Iridium flare due to the brightness (the peak was on par with the ISS or Jupiter, maybe a little more), but this wasn't a single *FLASH*, it was *blink-blink-blink* during it's entire transit of my sky. Increase in intensity seemed to mirror the decrease.

I keep going back to the 15 second cycle- I couldn't see any red or green blinks, I listened for anything that could have been engine noise and it moved pretty darn fast, so I don't THINK it was an aircraft. I've got to think it is a satellite that is spining, but I can't find any with a rotation that is a harmonic of 15 seconds.

Twinkling, not moving, star. Got it. Time to break out my old starguide book.

Hi Ironraven,

Could have been Aurora, the blink-blink-blink being the equivalent to the Donut on a rope contrail frequency during the nightime.



Was there a infrasound effect, something you couldn't hear but could feel in the pit of your stomach every 15 sec?