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Strange slow trail through M31 , NEO ?

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#1 steveward53

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Posted 08 September 2012 - 08:21 AM

While I was doing a drift-align with the camera on the 6th I picked up a short trail on one of the test frames , paid no attention to it until it appeared on the next nine frames too.

Each frame is a 60 second exposure and the FOV is roughly 4 degrees ( ED80 + F/F ) centred on M31 , 1st frame at 22:10 UTC , last at 22:22 UTC. Observed from 52.29963N - 0.49924E.

Was far too dim to pick up in bins and too slow for a satellite methinks !

Any ideas

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I've had a quick look at NASA's NEO site but got a little confused to be honest , maybe someone could input the details correctly for me , I'd be very grateful . :)

Steve.

#2 John Wunderlin

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Posted 08 September 2012 - 03:58 PM

I tried using the NEO checker from here:

http://scully.cfa.ha...in/checkneo.cgi

didn't find anything, but I'm not sure I converted into decimal time properly. Good luck!

#3 steveward53

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Posted 08 September 2012 - 04:22 PM

Thanks for trying John , I'll have a play myself and see what I can find.

Steve.

#4 GlennLeDrew

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Posted 13 September 2012 - 04:55 AM

I suppose it's possible it's a satellite or other piece of man-made stuff in a quite high orbit. If it were a small asteroidal body, one would think it would have been detected already by an automatic survey, especially given its position not so far from opposition. It would be useful to determine at least an approximate angular rate of motion, as this can supply constraints on distance, whether in Earth orbit or passing by.

Just by examining the sequence of your images, and picturing in my mind the geometry, I'll make a provisional analysis as though this were asteroidal. Again, this is purely hypothetical, based on mental 'back of the envelope calculations!'

It's motion is prograde, its orbit is tilted roughly 50 degrees to the ecliptic, and it very recently (within the preceding day) crossed the ecliptic going northward, meaning it crossed the ascending node.

The orbital inclination would depend of course on the relative speeds of Earth and the body; if the body is not so much faster, the inclination is steeper than 50 degrees, and if rather faster, the inclination is shallower. In any event, given that it's roughly opposite the Sun and is overtaking Earth, its orbit's semi-major axis is larger than 1 a.u., and it is on the way to perihelion, being closer to that point than aphelion. It's orbit certainly crosses the Earth's, and it spends rather more time outside Earth's orbit than inside.

Again, this is all hypothetical! If asteroidal, the fairly large angular motion implies a quite close passage at the time of your images. And given the nearness to the ecliptic plane would make this a *potentially very dangerous* Earth crosser!! And so such a fairly bright body must already have been discovered, which leads me strongly to the great likelihood of it being man made...

But you never know! Keep pressing for identification if man made; if nothing is forthcoming on that front and you've exhausted all avenues, be prepared to submit your data, including your best determinations of time.

#5 WillCarney

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Posted 13 September 2012 - 01:46 PM

If you go to calsky and put in your location and time you will find a lot of satellites during your time of exposure. A lot of these are slow movers. Not all satellites move fast. This is not all inclusive either. Many dim one's don't show on CalSky. You need a program that downloads the tle file directly and uses it for tracking. Several satellites take 5-8 minutes to cover the sky by the way. By the direction I would put this as a mostly polar orbiting object and most likely a rocket booster body or satellite. Envisat was close. The close asteroids at that time were 57083 2001OM31, 2001BJ6 and 5113 Kohno but none of those three had fast movements that would be noticable in even hours of exposure.

William

#6 steveward53

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Posted 15 September 2012 - 07:06 PM

Thanks for that guys ,

I'm really grateful for the time you've put in , it's humbling to be amongst people that know their stuff on here.

Steve.






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