Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Feb 24, 2010, 05:33:03

Title: Geostationary Satellite
Post by: MarkS on Feb 24, 2010, 05:33:03
I accidentally caught this while doing some focus tests on the yellow banana scope.  The camera (Canon 350D with wonky CCD) was set to take 30sec exposures with 30sec pauses during which I adjusted the focus.  This is a stack of 7.

A geostationary stays fixed in the same position in the sky.  The background star field will "move past" the geostationary at 360deg/day i.e. 15arcsec/sec.  Each of the "dashes" in the image below are 450arcsec (i.e. 30sec * 15).  That speed and the direction of travel relative to the star field are dead giveaways for a geostationary.  

For related info, here's an APOD of some geostationaries: http://apod.nasa.gov/apod/ap100220.html and it's associated video http://twanight.org/newTWAN/case.asp

At F2.8 I guess they're quite easy to catch!  ;)

Mark

(http://www.markshelley.co.uk/webdisk/geo20022012.jpg)
Title: Re: Geostationary Satellite
Post by: RobertM on Feb 24, 2010, 07:56:06
Smells of 'lucky cam' to me ;)

Nice fov with that scope and it's pulled in a lot of light for such short subs.  I guess you'll need sub-second exposures to stop the Trapezium burning out..

Robert
Title: Re: Geostationary Satellite
Post by: Rick on Feb 24, 2010, 09:46:43
To be honest, if you're pointed at that bit of the sky then the chances of your missing one aren't high...

Well spotted, though. ;)
Title: Re: Geostationary Satellite
Post by: MarkS on Feb 24, 2010, 10:00:04
That's right Rick.  I'm going to have a look at other subs I've taken over the years - I bet they're full of them.  I generally use sigma stacking for the final stack and so that always removes them from the final image.

As long as the satellite is not in the Earth's shadow then it ought to appear.
Title: Re: Geostationary Satellite
Post by: mickw on Feb 24, 2010, 10:47:13
Wouldn't be surprised if you captured the Iridium Cosmos crash  :roll:

(http://www.clicksmilies.com/s1106/lachen/laughing-smiley-014.gif)

Title: Re: Geostationary Satellite
Post by: Fay on Feb 24, 2010, 13:22:05
Looks very good for 30 sec exposures, Mark!
Title: Re: Geostationary Satellite
Post by: Rocket Pooch on Feb 25, 2010, 09:56:55
I like that esspecially with the diffraction spikes.
Title: Re: Geostationary Satellite
Post by: Rick on Feb 25, 2010, 11:15:54
Quote from: Space Dog on Feb 25, 2010, 09:56:55
I like that esspecially with the diffraction spikes.
Perfectly respectable diffraction spikes, those; tell you something honest about the objects images and the instrument used to image them.
Title: Re: Geostationary Satellite
Post by: Ian on Feb 25, 2010, 11:26:23
Quote from: Rick on Feb 25, 2010, 11:15:54
Quote from: Space Dog on Feb 25, 2010, 09:56:55
I like that esspecially with the diffraction spikes.
Perfectly respectable diffraction spikes, those; tell you something honest about the objects images and the instrument used to image them.
You sure? They look a little Carboni to me...

Title: Re: Geostationary Satellite
Post by: MarkS on Feb 25, 2010, 12:24:52
Quote from: Ian
You sure? They look a little Carboni to me...

The latest Carboni spikes are very realistic.  It's increasingly difficult to distinguish them from the real thing.
Title: Re: Geostationary Satellite
Post by: Rick on Feb 25, 2010, 13:23:21
Quote from: Ian on Feb 25, 2010, 11:26:23
You sure? They look a little Carboni to me...

I trust Mark not to put Carboni excressences on his images.

Quote from: MarkS on Feb 25, 2010, 12:24:52
The latest Carboni spikes are very realistic.  It's increasingly difficult to distinguish them from the real thing.

...thus making it more and more difficult to trust images on which his software might have been used. Doesn't make the forgery any less dishonest...