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Asteroid processing...?

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Hiya - I thought I'd have another go at getting some more 10min subs on NGC 7023 last night, with the imaging run starting at 23:31. When I loaded the frames into DSS I always randomly select a star to check each sub - The star I selected seemed to have a small red blob at about 4pm, which I thought might simply be a hot pixel...

The next frame had the same red blob, but it had moved slightly, and over the next 16 frames, that little red blob had moved at about 45 degress under that star and towards the edge of the frame on the left, so I'm assuming I inadvertantly captured an asteroid :eek:.

Now, here's the rub - I was hoping to make it into a gif, but although it's visble in DSS, when I convert the file to look at it as a tif or jpg in PS... It's not there :).

I've attached a couple of screen shots from DSS showing the little red blob (in the square zoom window top right), but has anyone got any ideas how (or if) I can do anything with this?

(Also, has anyone any idea how I can find out more about what this asteroid was/is?)



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Interesting, but I'd say it was an artifact or hot/dead pixel. If you flick between the two images, you can see that the stars jump across the frame so you have some drift or field rotation, so I suspect it's the red blob which stays put and it's the stars which are moving. In any case an asteroid wouldn't appear so red.

p.s. There don't appear to be any known asteroids in that area (at least, any above 18/19th mag)

Edited by lukebl
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Hi Luke - That was my first thought too, but the movement on that artefact over 3.5 hours + is VERY linear and the full frame of NGC 7023 certainly doesn't rotate by as much as would be indicated by the movement of that blob... Also whatever it is it doesn't rotate around that star but moves in a straight line underneath it... :)

Just for further info, the two screenshot frames above were taken at 23:31 and 00:36, and here are three more taken at 01:30, 02:34 and 03:17 (the last one).

(Maybe a near geo-stationary satellite?)




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Hi Andy,

You could be right. I just wondered if the red dot looked as though it was moving, but only because it was in a different position in relation to the stars. Are you certain that the dot is actually in a different position on each frame? Sorry for stating the obvious, but I find it fascinating!

Here's a quick animation of a couple of your frames to show the considerable drift in the stars over time (click on it to make it work).


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Hi Luke - Yes, I'm absolutely positively sure that the red blob is moving in relation to that star... If you look at the zoom window in that first jpg (Asteroid 1) and compare it to the last (Asteroid 5), you'll see that it's moved quite a bit in relation to that star (I've tried to keep it in the zoom window frame as best I can to show this...)

PS - Your gif of those two frames really shows up my poor polar alignment though (:eek:) but if that was the cause then the red blob would have stayed in the same position in relation to the star...)

I too find this fascinating - I can't even be bothered to stack the frames at the moment... I just want to find out what it is... :)

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Hi Luke - Yes, I'm absolutely positively sure that the red blob is moving in relation to that star...

I wasn't doubting that the red blob is moving in relation to the star, but just wondered if it was at the same pixel location on each frame, in which case it is an artifact on the sensor. As I said, if it is an artifact on the sensor it will look as though it's moving because you are stacking on the stars which themselves are clearly moving due to imperfect aligment or guiding....

....if you get my drift. Maybe I've lost the plot!

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Hi Luke - Ah, I get what you're saying...

If I can get the camera to the same temperature and take a few darks, I could then maybe have a look at those and see if there's a red blob in the same area... (Do you think that would prove, or disprove, anything?)

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Cheers Luke - I ordered the extension tube yesterday, so next clear night I can hopefully try it all out and see how it works. To be honest, those last DSLR subs on NGC 7023 were all-but wrecked by noise - I'd like to have finished that one off, and also a mosaic on IC 1396 (only 2 panes taken), but I think the 314L is going to take precedent now...

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