satellite?

[AlanThorpe]

Hi there,

Just last week saw what looked like a satellite near Cassiopeia.....but not like the

Usual fly past in the eye piece! I had a 32mm eyepiece in a 8inch Newtonian.

It took 3 minutes for this object/satellite to cross from one side of eyepiece to the other......it was moving very slowly from south to north.

What sort of high orbit would this involve?

Just thought it was a strange one!

Cheers

Alan

[Scorpius]

Who knows - but last time I got involved in one of these "what is it's", I nearly became obsessed with trying to figure it out. A member of SGL had video of a strange object passing in front of the moon but with no images or video to go by in this case, I'd be reluctant to even hazard a guess...

http://stargazerslounge.com/topic/249498-what-is-this/

[Dave In Vermont]

If you play with Previsat - a satellite-tracker you load with fresh TLE's - satellite-telemetry - available online through NASA, which it does with just a click of a button - then Previsat can identify many satellites up there and display where they are on a global map. You can set this map to update every 1 second, so you can see which are moving and how quickly.

Previsat is the easiest and most friendly satellite-tracker available. It is free to download and use - as are TLE's through the US government. But you will not be able to find out what a great many satellites are. They are government spy-satellites and such, so data on them is classified - even though you can see the little darlings. And, no doubt, they can see YOU!

Here you be:

http://sourceforge.net/projects/previsat/

This is freeware coming via SourceForge, the same folks you can download Stellarium from. They carry many good astronomy software-programs - Free:

http://sourceforge.net/directory/science-engineering/astronomy/os:windows/freshness:recently-updated/

Happy hunting!

Dave

[DRT]

I suspect what you have seen is a satellite in geostationary orbit.

Were you using a tracking mount? If so it was the scope that was moving, not the satellite

[Stu]

I agree, quite likely a geostationary satellite, although I've just discovered another type which may fit the bill. These are highly elliptical orbits, as described here and move N/S matching your description. At their highest, they move very slowly indeed.

https://en.m.wikipedia.org/wiki/Highly_elliptical_orbit

[brantuk]

Yup - that was my first thought too - geostationary satellite. The ones that aren't geostationary move through the eyepiece a lot quicker (seconds not minutes). If the scope was tracking then it would appear to take a few mins as the scope moves to counter the Earth's rotation. If the scope wasn't tracking - then the satellite would appear to stay still in the eyepiece. But then you'd have trouble identifying it as a satellite cos it's just another dot in the sky.

Were you viewing towards the south at the time? There's a lot of TV station satellites in high geostationary orbit around the south (and a degree or two SE). Hth

[michael8554]

To be Geosynchronous, a satellite has to be at zero Dec, over the equator.

Alan said it was in Cass, which is at about 60 Dec, and that it was in a NS orbit.

Polar orbits are usually low altitude, so a satellite would zip across your FOV.

As BigSumorian said, a very eccentric polar orbit could place a satellite at high Dec at it's highest point where it is travelling at its slowest, for Polar Icecap monitoring for instance, but that orbit would have been arranged to be over the pole in daylight I would assume.

Michael

[DRT]

To be Geosynchronous, a satellite has to be at zero Dec, over the equator.

That is geostationary, which is a type of geosynchronous. The terms are often confused, including by me above. Not all geosynchronous orbits are at zero Dec.

[Dave In Vermont]

"........................................

As BigSumorian said, a very eccentric polar orbit could place a satellite at high Dec at it's highest point where it is travelling at its slowest, for Polar Icecap monitoring for instance, but that orbit would have been arranged to be over the pole in daylight I would assume.

Michael

Could you explain what you mean ".....would have been arranged to be over the pole in daylight I would assume." Whose 'daylight' are you referring to?

Dave

[AlanThorpe]

Thanks very much everyone for the helpful replies! The highly elliptical orbit sounds like what I guess I saw! 35000 km altitude is incredible and to able to see little satellite moseying across the eyepiece was fairly funny! I wasn't tracking it...just had it pointing near Cassiopeia and then timed it traversing with the phone. Amazing how much stuff is up there in orbit!

Thanks again!

Alan

[michael8554]

Okay, my bad, I did mean Geostationary not Geosynchronous.

Regarding the daylight comment, as it's not midnight sun at high latitudes at this time of year, and assuming  this satellite is at the top of it's orbit and hence in a position to take images, for the purpose I suggested of Ice Cap monitoring, I would  take images during the day, and at the time Alan saw it, it was night, here in the UK and up to the pole.

Michael 

[Stu]

This page seems to imply that the highly eccentric orbit can be used for communications too, so perhaps the day/night thing is not always relevant?

Looks like GPS satellites may also be candidates as they are in relatively high orbits but I think the eccentric orbit is the most likely explanation.

http://m.earthobservatory.nasa.gov/Features/OrbitsCatalog/page2.php