Geosynchronous satellite trace

[Rob_K]

Amazing what you can see when you look a little deeper into your shots!

The "5 Asteroids & 2 planets" shot I posted earlier shows a faint trail of dots in the bottom right corner. I just cursorily dismissed it as a hot pixel trace (no tracking), but then it occurred to me that I had re-positioned the camera on the tripod 3 times during the sequence. A search of the original stack of 20 15-sec exposures revealed a hot pixel trace that did jump each time the camera was re-positioned (heavily stretched crop attached for reference).

So the 'object' appears to be real. The total elapsed time for the sequence was 9 min 30 sec, and the apparent movement against the starfield was 2.4 degrees, measured approx with the measuring tool in Starry Night Pro 5. This would indicate a period of about 24 hours - ie staying in the same spot relative to Earth while the starfield rotates (not quite true as apparently they do a slow figure-8 relative to the observer, unless geostationary). An actual size crop from the stack, labelled, is attached. On each frame, the object is considerably brighter, probably mag 7-8. Stacking has dimmed it, particularly to the left.

This would suggest a geosynchronous satellite, but I'd be interested to hear any comments from keen or knowledgeable satellite observers/imagers out there. Thanks.

Shot details: Canon 400D on tripod; crop from 20 frames stacked in Deep Sky Stacker, each 15 sec at 18mm, F/3.5, ISO 1600. Stretched in PS CS2 & saturation of asteroids included was selectively increased to 100%.

[monoxide]

i just checked and it looks like you captured the geosynchronous satellite BEIDOU 1D (mag 8.55)

checking again theres a very good chance that there is 2 other geosynchronous satellites in the full image, Sinosat 3 and Chinasat 6B

[Phoenix (Steve)]

Interesting photos Rob. I know a little more about earth polar orbiting satellites than I do geostationary, but what you have described makes sense. Geostationary satellites are typically equatorial and find their equilibrium at about 36,000K above the Earth's surface so if you were imaging north of your latitude (towards equator) then this would add some support to your theory.

Cheers

[Rob_K]

Thanks Steve & Monoxide! Monoxide, thanks for that information - I would love to know what sat tracking program you are using. I've tried a couple without success. The info I got on BEIDOU 1D says that it is in a geostationary orbit at 86 degrees east. From my position, I think I would be looking considerably further east than this (ie it was almost due NE from my location in North-East Victoria).

Trying to grapple with the geometry of it all - geostationary satellites track directly over a point on the equator, and with parallax you'd expect to see them just north of the celestial equator, when viewed from the S Hemisphere. This ties in with my 'object', as it appeared to be about 6 degrees north. Geosynchronous wander, but still are in the region of the equator. I think ! Aaarggghhh! Stick with asteroids I think

[monoxide]

not sure what it is then Rob, i changed my location to vic and had another look, i've attatched a screenshot

[Rob_K]

Thanks Monoxide. Last night, I used Starry Night Pro 5 to try to image Beidou 1D, Sinosat 3 and Chinasat 6B, but they weren't in the positions indicated by SN (quite bright at the times I tried, all stated at about mag 8.5). At just after 10pm though, I picked up a faint trace in the north-west (attached). My viewing position is 36.750S & 146.967E.

I've tried SatScape, but can't seem to get it to work properly. If you or anyone else could suggest a good program, I'd be very grateful.

Cheers -

[monoxide]

the only other one ive used is orbitron
http://www.stoff.pl/

[Mick (Michael)]

Hi Rob nice work,

I was wondering if your geo might be Optus b3 or Optus c1? Orbitron shows a few near that location. It's a shame your series of images didn't last a bit longer some of those satellites are eclipsed at that time as well. There is an older thread about Optus b3 here that you may find interesting, it has some good information and links to geo tracking programs.

http://www.iceinspace.com.au/forum/s...ad.php?t=16246

[Rob_K]

Thanks Mick - still trying to work out Orbitron! Some good links & interesting background there. The 2 sats you mention are probably a bit too far west to be the one in the second image I posted.

I got the first one again tonight (almost due NE from my location). Image attached, a stack of only 8 untracked exposures this time. The shot has a cast of thousands, possibly the most cluttered image ever posted on IIS .

My apologies!

Cheers -