C27 - The Crescent Nebula in Cygnus - First Light - NB - WIP

[peter shah]

nice work

[Gina]

Thanks Peter

[astro mick]

Nice one Gina.You certainly seem to generate a lot of comments.

Nice outer shell.

Mick.

[Gina]

Here's a go with long subs only viz. 4x10m Ha and 3x20m OIII. Stacked in DSS, aligned with RegiStar and combined and stretrched in PS CS5. R = Ha, G = OIII, B = 24% Ha +OIII. Slightly cropped to remove framing errors. No sharpening or other filtering.

[WaveSoarer]

That's very nice.

[Gina]

Thank you

[Gina]

Following PA using AT last night, I collected further Ha and OIII data for the Crescent. I now have 12x10m of Ha and 10x20m of OIII. I'm not using any of the shorter subs. As usuak stacked in DSS, aligned in RegiStar, combined and processed in PS. R=Ha, G=OIII and B=25%Ha+OIII. Slightly cropped.

[michael.h.f.wilkinson]

Very nice result. Awesome image

[Gina]

Thank you Michael

[MartinB]

You're putting a great set of data together Gina, starting to look really good. We all have our subjective opinions but for me, the OIII is a bit "in your face". I think a bit less stretching might give a cleaner, more natural looking image.

Sorry to be dumb but what does "following PA using AT" mean?

Regarding combining subs of different lengths. This can be achieved using "normalisation" during stacking. Lots of stacking software will, if asked, look at an even part of the image of mid range brightness and use this to provide appropriate adjustments to brighter and dimmer subs in relation to the reference image. Both Maxim and CCDstack do this nicely (CCDstack gives better control over the process). I would have thought DSS would have a facility to do this. To fine tune this, using CCDstack you can stack a set of subs with the same exposure time and then use this as the reference image for normalisation (not so easy with Maxim). CCDstack is a terrific programme but I tend to stick with Maxim which delivers good results. Sorry I can't advise on DSS

[WaveSoarer]

Wow Gina. That's amazing. The image is just getting better and better. It's so rich and detailed.

[Gina]

You're putting a great set of data together Gina, starting to look really good.

Thank you Martin

We all have our subjective opinions but for me, the OIII is a bit "in your face". I think a bit less stretching might give a cleaner, more natural looking image.

Could be Maybe a different balance between the fainter OIII and the brighter would be better.

Sorry to be dumb but what does "following PA using AT" mean?

I started the night doing polar alignment using AstroTortilla, getting the PA as good as I could, ending up with the most minute shift of knobs or lkever on the adjusting bolts. At one stage I was 30 arc seconds off but when I tried to get it better the next reading was over 3 arc minutes the other way and I'd barely touched it. Next attempt halved this error so I decided that would have to do. I have another thread in the "Observatories" forum discussing PA adjustments.

Regarding combining subs of different lengths. This can be achieved using "normalisation" during stacking. Lots of stacking software will, if asked, look at an even part of the image of mid range brightness and use this to provide appropriate adjustments to brighter and dimmer subs in relation to the reference image. Both Maxim and CCDstack do this nicely (CCDstack gives better control over the process). I would have thought DSS would have a facility to do this. To fine tune this, using CCDstack you can stack a set of subs with the same exposure time and then use this as the reference image for normalisation (not so easy with Maxim). CCDstack is a terrific programme but I tend to stick with Maxim which delivers good results. Sorry I can't advise on DSS

I think I've heard of this but I think it's easier to just keep to the same sub lengths

[Gina]

Wow Gina. That's amazing. The image is just getting better and better. It's so rich and detailed.

Thank you May get some more tonight if the weather permits. The forecast keep changing from clear to cloudy and back again! So I'll just have to wait until dark and see.

[StuartJPP]

Looking good Gina.

[Gina]

Maybe this is better Martin...

[MartinB]

Personally I love the colour in post #29. Also in that image the top left rim of the crescent isn't burnt out. Something like that but smoother with the extra data would bring out a wow from me!

[Gina]

Cloud last night stopped me adding any data but here is another reprocess with care taken to preserve the detail in the brighter parts and get the brightness/contrast as good as possible throughout the brightness range. I have also applied a small amount of sharpening. Colour contrast has been enhanced using Lab Colour and 30% contrast increase in the "a" and "b" channels then returning to RGB Colour. This is the full frame without any cropping.

[MartinB]

Wow

[MartinB]

Hope you don't mind the nit picking Gina but some of those brighter stars are a bit burnt out and hard edged. A quick and dirty trick in PS is to zoom in on the star you want to adjust and use the blur brush around the edge of the star. Then use the minimum filter positioned around the blurred margin giving the selection a small feather. I've tweaked the central star and am attaching a before and after.

[ollypenrice]

This is a great image. The O111 'cling film' around the Ha nebula is fabulous.

Olly

[Gina]

Hope you don't mind the nit picking Gina but some of those brighter stars are a bit burnt out and hard edged. A quick and dirty trick in PS is to zoom in on the star you want to adjust and use the blur brush around the edge of the star. Then use the minimum filter positioned around the blurred margin giving the selection a small feather. I've tweaked the central star and am attaching a before and after.

I don't mind Martin I agree that the brighter stars are well and truly burnt out. Sometime I'll try a star removal and replace - I've still got a lot to learn but I'm enjoying it and I think my processing is improving all the time. Practice, practice, practice Yes your tweak does look better Thank you

[Gina]

This is a great image. The O111 'cling film' around the Ha nebula is fabulous.

Olly

Thank you Olly Praise from the great is much appreciated

[andyo]

Gina this now looks stunning the outer shell is fantastic well done

[robin-m]

+1 for longer subs. The following two images are stacks of 24 15 minute subs (6 hrs) vs 4 30 minute subs (2 hrs). Both have had exactly the same processing applied to them and were taken on nights with very similar seeing. Despite having 1/3 of the total integration time the 4 * 30 minute trounces the 24 * 15. I was really surprised by the results when I saw them. I'm now going to see if I can tweak my PA a little more, finally sort out PEC and see if I can stretch to 1 hr subs although that might be a bridge too far for my poor little HEQ5....

NGC7635 24 * 900 ha, scaled 1:2, cropped and saved to jpg

NGC7635 4 * 1800 ha, scaled 1:2, cropped and saved to jpg

[Gina]

Thank you Andy Have to say I'm quite pleased with this one I also have to say, I'm delighted with my equipment. The MN190 is a superb scope and the same applies to the Atik 314L+ mono camera plus EFW2 and Astrodon filters. OAG and Lodestar is definitely producing better guiding too.