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jmX
super member
Reged: 04/23/09
Posts: 164
Loc: Orange County, CA
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So, I shot the orion nebula this weekend for the 2nd time, and again, I got satellite streaks in the photo. The imaging time was from 1:40am to 2:20am Pacific Time. Now, I always thought that satellites were reflecting sunlight down at us, and that created the streaks. I understand its very common 1-2 hours after sunset, and 1-2 hours before sunrise, but how can this happen at 1am, when sunset is at 7pm and sunrise is 7am?
Anyway, I digitally removed the streaks, but I'd still like to understand where the satellites were being illuminated from.
The brightest streak took nearly 9 minutes to cross the frame from top to bottom, so I assume that one was a Geosynchronous satellite....still seems like it should have been dark tho. Possibly this exact same satellite crossed orion last month when I was imaging it, as again it took 9 minutes to cross the frame.
Here's a b/w preview version showing the brightest 9 minute long streak before I digitally removed it:
The results (after removing the streaks) are here:
Bigger Version Here
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gavinm
scholastic sledgehammer
Reged: 08/26/05
Posts: 804
Loc: Auckland New Zealand
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Satellites can be seen at any time of the day or night. The ISS is only seen at the limited times you mention because it has such a low orbit (~300 km) that it is often in Earths shadow vs geosynchronous (~35,000km) which are almost always illuminated.
PS nice image - i like the colours
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Gavin
Mt Albert Grammar School Observatory
Auckland, New Zealand
http://www.mags.school.nz/astronomy/index.html
12" LX200R F6.8 AP
SBIG ST7-XME + CFW10
Moonlite SCT focuser w/ temp
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+ other stuff
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gavinm
scholastic sledgehammer
Reged: 08/26/05
Posts: 804
Loc: Auckland New Zealand
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A quick bit of maths (without a calculator) seems to result in a period of well over 24 hours, but more likely a slower speed during that part of the orbit, ie highly elliptical. That might indicate one of the US communication satellites (seeing as you live in Ca) - thats a guess by the way
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Gavin
Mt Albert Grammar School Observatory
Auckland, New Zealand
http://www.mags.school.nz/astronomy/index.html
12" LX200R F6.8 AP
SBIG ST7-XME + CFW10
Moonlite SCT focuser w/ temp
Skywatcher Equinox ED80 Pro (ADM dovetail)
+ other stuff
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jmX
super member
Reged: 04/23/09
Posts: 164
Loc: Orange County, CA
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Quote:
A quick bit of maths (without a calculator) seems to result in a period of well over 24 hours, but more likely a slower speed during that part of the orbit, ie highly elliptical. That might indicate one of the US communication satellites (seeing as you live in Ca) - thats a guess by the way
I'd be kinda shocked to think that a satalite 22,000 miles away could be seen in a shot at 400mm though. Does that seem right? It must be gigantic if thats the case.
Even if the sat isnt in an eliptical orbit (Seems strange that it would be) it still makes sense that it'd leave a streak since the earth and the satalite are both rotating, but the starfield is not, and thus, it will appear that one is streaking past the other.
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Jon
C6N + CG5
Skywatcher Equinox 80 + CGEM
http://jmx.ls1howto.com
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gavinm
scholastic sledgehammer
Reged: 08/26/05
Posts: 804
Loc: Auckland New Zealand
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It is kinda weird I agree, but we're using very sensitive cameras these days and satellites are very reflective. Geostationary satellites pop up all the time in images. An easy way of determining if you got one is to simply turn off your drives on the mount. The stars will streak, but you will end up with dots for the satellites (the opposite of what you got). You may even see a few in a dead straight line.
Eliptical orbits are used to ensure that a satellite spends more of its orbit over one location eg US. The eliptical geosychronous orbits (vs equatorial geostationary orbits) are used when you need north/south movement - This is when its at its furthest point and travelling the slowest - thats why I think its one of yours. Another check that its geostationary is - Is it south from you? - eg above US again. Geosynchronous satellites can almost be as far north as the artic circle.
Have a look at this 
http://epod.usra.edu/blog/2007/09/geostationary-satellites.html
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Gavin
Mt Albert Grammar School Observatory
Auckland, New Zealand
http://www.mags.school.nz/astronomy/index.html
12" LX200R F6.8 AP
SBIG ST7-XME + CFW10
Moonlite SCT focuser w/ temp
Skywatcher Equinox ED80 Pro (ADM dovetail)
+ other stuff
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jmX
super member
Reged: 04/23/09
Posts: 164
Loc: Orange County, CA
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Man, there's tons of them lined up there in a row. No wonder I've gotten 2 through my Orion shot both times I've tried to get 1 hour of data. It must be that orion passes right through the lane of them at the time I'm shooting. Doh!
Thanks for the link.
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Jon
C6N + CG5
Skywatcher Equinox 80 + CGEM
http://jmx.ls1howto.com
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Raven911
Carpal Tunnel
Reged: 03/12/05
Posts: 1815
Loc: by Cloudcroft, NM
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It is extremely hard to image Orion without getting at least one satellite in the picture.
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http://smg.photobucket.com/albums/v287/Raven911/Astrophotos/
http://www.eye-of-the-raven.blogspot.com/
My list of second-hand and home-made stuff:
Celestron SC6
Celestron C9.25
100mm F6/76mm F4.5/80mm F5/SV NHII 80mm F6 Achros
SBIG ST7/Canon 300D/DSI Pro Mono/Starshoot DSCI
8 inch F7 Newt on Edmund EQ
8 inch F4.5 Project Astrograph
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DaemonGPF
Post Laureate
Reged: 03/22/08
Posts: 3567
Loc: New Mexico
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Agreed. Orion is a satellite magnet. You'll constantly see streaks through there. You should go find your raw subs and sequence them in a gif file to animate the motion. If you have the precise times, you could potentially look up the object and then label your image which would be pretty nifty.
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-Josh
http://cleardarksky.com/c/AlbuqNMkey.html
My AP Gallery
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