Sculptor Galaxy

[Paul Haese]

Had an opportunity to grab some data on the Sculptor over the weekend. The seeing was fair to average. It involved two sessions over two night and I expect I will grab more data in the coming month.

Data taken with QSI583 WSG
LRGB 120 65 65 65

Click Here for image (http://paulhaese.net/NGC253QSI9-10oct2009.html).

I think I need to do more on deconvolution and sharpening. Overall I think it is better than my previous images. Guiding is still causing trouble, I need to beef up all my connections and prevent any flexure. The guide scope is 700mm and the main scope is 1625mm. That is bound to cause problems.

Would appreciate constructive criticism and comments.

[allan gould]

Very nice, Paul. I love this galaxy and ant get enough of it. You have done a great job with it - very smooth and good guiding

[TheDecepticon]

Very nice, Paul! I think the guiding isn't too bad, have seen worse.:eyepop:

[danielsun]

Stunning Paul.:thumbsup: That is a beautiful image, even if you had guiding issues the result is very nice .;).




Cheers Daniel

[rat156]

Hi Paul,

Not too bad, but the guiding does need some work. Are you using the OAG in the QSI?

I'm finishing this one off tonight with my setup, should be a nice comparison, same scope, different camera.

I think that you should try a different method to stretch your images as the stars have been saturated at some stage. If you're using a curves type stretch, remember what Wodaski mentions in "the Zone", straight to the end. Your curve should be nonlinear at the dark end, but then go linear towards the white end. This usually stops the stars from blowing out.

Cheers
Stuart

[Paul Haese]

Thanks guys, I reprocessed image and the link below has replaced the previous image. It is much sharper than before and I did Ken Crawford's tutorial.

Click Here (http://paulhaese.net/NGC253QSI9-10oct2009.html)

[Hagar]

Guiding can be a real ***** of a thing to get just right but I'm sure you will work it out.
The image and general detail is very good.
As Stuart pointed out you stars may be a little over cooked and may benifit from creating a star mask earlier in the processing sequence which could prevent the over saturation.
As for sharpening be careful of the stars in the galaxy they look like they have aready been quite heavily sharpened and may benifit from manual selection and a bit of Gausian blur rather than much more sharpening.
A few things to think about. But a nice Sculptor image.

[Paul Haese]

Thanks Stuart and Doug, not sure if you saw the reprocessed version of the image. I just posted it on the site about 10 minutes ago and you might have seen the previous image.

I used masking all the way through to prevent the star from being sharpened at all in the sky sections but the stars in front of the galaxy do seem over sharpened. I will look at these later.

The pursuit of perfection is difficult and I can say I am far from it at present. Ken Crawford's tutorial is really good though and worth checking out.

[Paul Haese]

Stuart, I am not using the OAG. It is proving difficult to use with the RC. Stars are slightly out of focus and oval. This makes for difficult guiding. I will give it a shot with the TSA in a month or so just to see how it goes on that scope. Otherwise I have to deal with flexure, which is my main issue I think with the shape of the stars. It is a pain.

[allan gould]

Paul, Ken Crawford's tutorials are brilliant and certainly well worth looking at. The re-processed image is a lot better after all your work. Well done on a great image.

[StarGazing]

What a cracker of a photo ....... you have done very well.
Thanks for that, amazing.
Alex.:thumbsup:

[AlexN]

With modern guiding programs, slightly out of focus and distorted star images should have little effect on guiding.. I reckon give it a fly despite what the stars look like.. You should find that it wont make much difference at all.. When I used an OAG with my C11 the stars were horribly out of shape, didn't seem to affect guiding at all.. same with using the ST9E's self guide chip... I must say, I don't know just how distorted the off axis stars would be in the 8" RC but I'd imagine them to only be slightly skewed... ?

Great image in any case Paul. The repro was very nicely done! Colours and detail both look very good.

[spearo]

well done
i dont think the difference in FL of the two scopes will matter to the guiding process actually
Software now picks up on minute changes
frank

[AlexN]

Frank is correct - He has beautifully guided his C14 @ F/11 with his WO ZS80 refractor before.. I too have guided my C11 @ F/10 with a WO ZS66.. Focal length makes little difference to guiding performance.

[Paul Haese]

So it is really flexure. Mind you the guiding does need some looking at. Finding the correct settings is the hard bit.

[gbeal]

I'm with the masses, it is a stunner.
I also believe the difference in respective focal lengths is not the issue. To prove this I went through a stage of using a converted 50mm finder for a guide-scope, with the QHY5 unceremoniously stuffed in the rear. Worked a treat and guided a nice NGC5128 taken at 1800mm with my Mak.
I reckon also to try the OAG since it is there and see. While the visual look may be ugly, like has been said, the pixels may not care.
Gary

[AlexN]

Paul - What software are you using for guiding? In PHD you can set the min pixel movement that will initiate a guide pulse, you can do the same in MaximDL as well, Im not too sure about CCDSoft, I never really fiddled with settings in CCDSoft...

If you work out your arcsec:pixel ratio for your guide setup and for your imaging setup, then work out what amount of movement in a guidestar will affect the image in the imaging setup, you can fine tune the guiding that way. From there, just adjust the aggressiveness so it doesn't overshoot... Im lucky at the moment, because my guide setup has 1.04" per pixel and my imaging setup is close to 3.5" per pixel, even on nights of very average seeing and a gusty wind, I dont get guide issues.. I've also removed every possible moving part from the setup. Things like guide rings (which I know you dont use) synta style rings etc.. I also make sure to use as many extension tubes as possible, so my focusers are always only racked out a little bit, the furthest I rack out either of my focusers is 2.2cm. they are then locked down firm...

Im sure you've looked at all these things to sort out your issue... just thought I should add them incase...

Alex.