Pacman Nebula

[Ceames]

Here's my first go at the Pacman nebula, taken last Monday night.  60x90s unguided subs stacked in DSS with about the same number of darks and flats etc.  I took 120 subs but ended up throwing half away as I'm really pushing the limits of my setup and I think there must be quite a bit of periodic error in my mount. 

I'm pretty happy with how it came out, although I did have a strange diagonal line in the stack which took a lot of editing out in PS.  Not sure what caused it, but it definitely came from the lights rather than the calibration shots and it was in enough of them that it must be from the scope setup rather than the environment.  It doesn't seem to have recurred though so I wonder if it was a strand of cobweb across the end of the dew protector.

Cheers,

C.

[xtreemchaos]

great image mate, well done. thanks for sharing. charl.

[feras281]

thats really impressive work , well done, you did it with very modest equipment ! 

[Knight of Clear Skies]

That's very good for an unguided image. Even using short telephoto lenses I end up throwing away a fair number of subs taken with my EQ3-2, I've never quite worked out what is causing the periodic error.

[laudropb]

Lovely image. Thanks for posting.

[Ceames]

Thanks for the kind comments everyone!

Cheers,

C.

[StargeezerTim]

I really like this image... Well done... must see if it is in range for me...Tim. 

[Ceames]

Thanks Tim

[glowingturnip]

that's very nice mate, amazing considering it's unguided !

Your diagonal line on the lights - was that in the same place on each light relative to the frame (i.e something to do with the telescope set-up) or was it in the same place relative to the stars ?  I'm processing a Pelican at the moment which has a diffraction spike showing from a star that's out of shot (Deneb), and possibly yours is similar if it is in the same place relative to the stars, I think the Pacman is quite close to Sadr.

How did you process it out btw, I'm starting to think of ways of removing mine too - fortunately it doesn't go over anything important, but it would throw the composition off if i cropped it out, and I want to avoid an excessively long clone-stamping session if I can.

[Tommohawk]

Great image especially given its unguided - and nicely processed too.

[Ceames]

Thanks guys!

Stuart, I think you may be right - I hadn't considered a diffraction spike from something out of frame...  I've attached the image with minimal post processing (just a crop, some aggressive stretching and a size reduction to get a small jpeg) which shows the line.  It does seem to be pretty much parallel with the other diffraction spikes, and according to Stellarium it is pointing roughly in the direction of Shedir in Cassiopeia so possibly mystery solved!

To get rid of it I ended up clone stamping it out either side of the nebula in a layer under the image and then using the eraser on the top layer to let the clone stamped layer through where the line was (following some advice from Olly I found on another thread on SGL!).  I didn’t really know how to deal with the line actually in the nebula itself so I left it alone and luckily it is not too noticeable in the final image.

Cheers,

C.

[Tommohawk]

Are you referring ot the line that goes pretty much right across the frame? Agreed its parallel to the spikes, but it's huuuuge. Also a bit curved I think.

More like a hair in the works somewhere?

[Knight of Clear Skies]

I'm pretty sure it's not a star causing the artifact, there are no really bright stars that close to the Pacman as this wide shot shows:

I agree with Tommohawk that it's likely to be an obstruction in the imaging train somewhere. You've done a good job of processing it out in the first image you posted.

[glowingturnip]

agreed, it does look a bit curved, so might not be.  Is it in the same place relative to the stars or relative to the frame in each sub ?

You've done a nice job of removing it though

[Ceames]

It could very easily be a hair or cobweb in the imaging setup - I can't find any evidence of it on the flats I took directly after the lights/darks which is what made me think something across the end of the dew shield was the most likely as I took that off to put on the cover to take the darks.  At any rate, it doesn't seem to be there in any of the imaging sessions I have done since then and it didn't have to much impact on the final image above so I'm happy enough.

Thanks for everyone's help!

Cheers,

C.

[des anderson]

WOW... that`s awesome,you must be chuffed,and unguided....just brill,thanks for sharing.

[samgray128a]

Don't know anything technical about atrophotography or indeed anything at all about it but that image looks gorgeous to me. Well done; very interesting to see so thanks for posting.

[Astrosurf]

That's a brilliant image! Really nice star colour too. Just goes to show what you can do with a basic set-up. Excellent job.

Alexxx