I just slewed to the Rosette Nebula and noticed an object blink. Then there was another bright yellow blink a few seconds later. I observed for a number of minutes and it continued to blink, except that it wasn't in the same place. It wasn't moving on the celestial sphere. Like a geostationary satellite, it stayed in the same place in the sky. I turned off the motors and now have the scope pointing toward it. (though it's a bit hazy, so I don't know whether I'll be able to observe it again) My grandmother saw it, too, so it wasn't my imagination. But do geostationary satellites blink?

You don't tell your location. That's very important to this.

A geostationary satellite would be slightly below the celestial equator, How far depends on your latitude. That's assuming you are north of the equator. If south then of course it would be north. Since the center of the Rosette is about 5 degrees north if you are located at 30 degrees south latitude, say Australia, then yes it could have been one but I've never heard of one blinking.

Also how long did you look? The rosette is listed in my book as 1.3 degrees. It would take a bit over 5 minutes for the satellite to drift across the nebula.

For checking your latitude against the declination of the geostationary belt see the first chart at:
http://www.geo-orbit.org/sizepgs/decchartp.html

Early geostationary satellites used spin stabilization in which part of the satellite spun thus could blink if the sun angle was just right. I don't think any of those are still in use. But once out of service all types are usually put in a non geostationary orbit to clear the orbit for a replacement. These then tumble slowly and orbit very slowly in relation to the turning earth. If put in a lower orbit the declination would be somewhat greater than shown on the chart since it would be closer, increasing the parallax.

Rick

I am at 42 degrees North, 72 degrees west. I did not check how long I was looking at it for, or whether it completely crossed the nebula. Infact I didn't even see the nebula, just the star cluster, so it might not even HAVE been the Rosette. (the goto was acting up)

Then it can't possibly be a geostationary satellite would be 6.5 degrees south declination at your latitude, about 11 degrees south of where you were looking. I doubt your goto was that far out of kilter!

The cluster for the Rosette is rather course, bright and sparse. A nebula filter helps a lot to see the nebula. If you have any light pollution it can be difficult without one. Though with a Lumicon UHC filter I had no trouble seeing it without any other optical aid from a city of 150,000. It wasn't hard at all which surprised me at the time.

Rick

Then what was it?

Geostationary satellites nearing their end of useful life are often kicked into a somewhat higher orbit to avoid confusion in the geostationary zone. And once stationkeeping to counter perturbations from Sun and Moon is turned off, the orbital inclination and eccentricity will change over time. So this could still have been a defunct formerly-and-now-almost-geostationary object. There are people who keep track of high-orbiting satellites telescopically (example here), and some of those resources could help track this one down.

Siguy,

It's possible that you saw a satellite in a Molniya orbit. These Russian "part-time geostationary" communication satellites have highly eccentric, high inclination orbits.

http://en.wikipedia.org/wiki/Molniya_orbit

http://www.centennialofflight.gov/es...NIYA/DI166.htm

http://members.aol.com/_ht_a/hattonj...p/MOLNIYA.HTML

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But do they blink from invisible to magnitude 7 (my guess)?

Anything tumbling or rotating (natural or artificial) can blink.

Think about how the surface area facing you of a cylinder would change as its tumbling on all 3 axis.
Now imagine it in a totally dark room lit with a small spotlight/pinlight on it.

I've seen quite a few blinking objects with telescope or binoculars, I assume that most of them (if not all) are old rocket boosters and assorted flotsam, tumbling in orbit.

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I hardly have a night where I don't see a satellite cross my FOV as I'm looking at something. There's a lot of junk up there, and the "tumbling" conjecture is a pretty good one IMHO.

It is now 10 days since the original post. Is it still there? Granted the angle of reflection will have now changed and it may be some time until the earth is once again in the right postion to repeat the effect, If it is there I would vote geostationary. Otherwise the jury is out but I would bet on a bit of tumbling junk that will eventually move on.

Kind regards
Matt

As I posted before. IT CAN'T BE A GEOSTATIONARY SATELLITE. As seen from his latitude 42N the geostationary belt, due to parallax is 6.5 degrees south decliniation. He was looking about 5 degrees north declination. While geostationary satellites to fly a figure 8 pattern they must stay within the bandwidth of a fixed satellite dish so can't move more than a fraction of a degree. The figure 8 pattern is very small as seen from earth. If raised to a higher orbit when its service life is over that would only move it a bit north. Even at distance of the moon it would still be somewhat south of 0 degrees declination. Out of plane maneuvers take a lot of fuel. Something a geostationary statellite at the end of its life is almost out of. It could be the result of a failed geostationary satellite but certainly not a working one or one that has been retired. I don't know enough about the Russian polar communication satellites to know if that's a possibility. When nearly stationary they are over the north pole and no where near the equator, especially on our side of the earth. I have a friend who used to monitor them with a big dish in his back yard, I'll see what he knows. My guess is it is just very high space junk. Many times I've had space junk show up in a short exposure taken to center an object or check focus. If it is moving very slowly then the trails start and stop points are both recorded. A true Geostationary satellite would cross my FOV in about a minute. Some I've recorded take 30 to 50 seconds judging by the length of the trail and the time of the exposure. indicating there's lots of very high junk up there. Nearly all of it tumbles. Visually it would be moving but very slowly, at low power in a undriven scope the motion would be hard to detect.

Rick

Thanks Rick. I stand corrected.

Kind regards
Matt

I talked to a friend who is far more up on satellites than I am. He tracks those Russian over the pole communications satellites -- he speaks Russian as well as true geosationary ones. He didn't think what Siguy saw was a dead over the pole Russian communications satellite. When seen that far south of the pole they'd be moving rather rapidly and the motion should have been obvious.

He also mentioned that a few true geostationary satellites had problems that took them out of service early in their lives when the still had plenty of fuel. Again, he only keeps up on live ones but he said a couple may have still had sufficient fuel, if it was all used, to go that far out of plane. Of course some fuel is still needed to also change the orbital height so it doesn't come crashing through the satellite belt every 12 hours. He didn't know for sure but looking at their specs and when the died it might be possible to do both. But he didn't know if that was actually done. Since you get more separation changing the orbit height he thought that is what they'd do but he was only guessing. Maybe someone out there knows the procedure with such early deaths. He didn't say if any were the older type that used spin stablization and I didn't think to ask. If it was such young dead satellite it would moved a degree an hour against the stars, mostly north to south and that should be obvious in the scope over a few minutes time.

The mystery continues.

Rick

Iridium flare?
http://satobs.org/iridium.html

Woah... Old topic. It was absolutely not an iridium flare, I have seen an iridium flare before. This was something that blinked on and off, for a long time, and stayed in the same place, unlike an iridium flare which gets very bright briefly as it moves across the sky.

That was a long time ago that I saw it, but I still have no idea what it is...

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