M17 Swan Nebula in HaRGB, 13hrs total

[Bassnut (Fred)]

Hi Guys

M17 Swan Nebula in HaRGB 13hrs exposure time.

3nm Ha 10hrs (30 off 20min subs bin1); RGB each 1hr ( 6 off 10min subs bin2).

Taken on a Meade 12" LX200R OTA, G11, ST10XME, at f6.7.

http://fredsastro.googlepages.com/home

Learnt an interesting thing through hrs of trial and error. I usually use STD sigma data reject in CCD stack (its the 1st on the list, what do I know?), but tried Poisson Sigma on M20, after watching a Guru how-too video. Poisson Sigma is much more agressive and leaves no bad bits. Very smooth and crap free BUT, if your stars are not all near perfect in every sub (eg eggy), it butchers them to hell, and artifacts appear really quickly with deconvolute. STD sigma seems to leave them alone, but some work in PS is required to clean up. Small point you say, but hugely time consuming to trial properly, results can be very different.

Anyway, I think the star thing is slightly better on this one, still working on that, Mike will no dought crucify me again . And maybe Jase might recommend his lose-the-stars trick, which I will do if he or someone thinks its worth it.

Thanks for looking

[gregbradley]

Hi Fred,

Where's the link dude?

Greg.

Originally Posted by Bassnut

Hi Guys

M17 Swan Nebula in HaRGB 13hrs exposure time.

3nm Ha 10hrs (30 off 20min subs bin1); RGB each 1hr ( 6 off 10min subs bin2).

Taken on a Meade 12" LX200R OTA, G11, ST10XME, at f6.7.

http://fredsastro.googlepages.com/home

Learnt an interesting thing through hrs of trial and error. I usually use STD sigma data reject in CCD stack (its the 1st on the list, what do I know?), but tried Poisson Sigma on M20, after watching a Guru how-too video. Poisson Sigma is much more agressive and leaves no bad bits. Very smooth and crap free BUT, if your stars are not all near perfect in every sub (eg eggy), it butchers them to hell, and artifacts appear really quickly with deconvolute. STD sigma seems to leave them alone, but some work in PS is required to clean up. Small point you say, but hugely time consuming to trial properly, results can be very different.

Anyway, I think the star thing is slightly better on this one, still working on that, Mike will no dought crucify me again . And maybe Jase might recommend his lose-the-stars trick, which I will do if he or someone thinks its worth it.

Thanks for looking

[Bassnut (Fred)]

hehe Greg, a quick edit, do you receive this via email?

[strongmanmike (Michael)]

OK..bring me the nails .....

Still, I admire your tenasity and persistence, please tell me this is all automated..?

Might still get you an APOD of course (you did use an SBIG after all) Perhaps remove the stars and distort the image a bit maybe?...and see what they think?



Mike

[Bassnut (Fred)]

Hehe, thanks Mike, yes, the left mouse clicking arm in PS is automated (after I buggered the right arm, doing the same thing, seriously).

Yep, image distorted and stars gone soon, SBIG is humming and its all go .

[jase (Jason)]

No Fred, the stars must stay this time...this is because nebulosity doesn't fill the entire frame. Dare I say it, but I think you shouldn't have put the F/R in the optical train. You'll find removing the stars will look hideous as the sky background is present. A suggestion, don't think you are limited by the one combine routine for your data. You can use STD SReject for star control and Poisson SReject for nebulosity. Thus, you'll give smooth nebulosity (and tight after deconv), but with nice looking stars from the STD SReject data. Perhaps use lighten or overlay blend modes. Egg shaped stars are egg shaped stars, it takes some crazy processing efforts to correct them. Its typically easier to recollect data. You may also have greater success if you create a synthetic lum from the RGB data - assuming the stars look tight. A great piece of work. Well done. Doesn't top your lagoon. It will take some considerable effort to do that, but you've got the persistence to make it happen.

[AlexN]

another marathon worth of lights culminating in another stunner...

Well done Fred.

[bluescope]

Well done again Fred but I think M17 needs to be imaged with a wider fov because, to me at least, the interesting structures are in the tail so to speak ( the curly bits ).

Ofcourse this is just a personal preference and isn't meant as a criticism of your technique.

You have the patience of Jobe doing these extreme long exposures, I assume you set and forget with the appropriate software or am I wrong.

Cheers

[iceman (Mike)]

I love the intricate detail in the middle. That's nice work there Fred. Mega exposure!

[marc4darkskies (Marcus)]

Very nice Fred! Colour-wise, definitely one of the more pleasing Swans I've seen too!

Cheers, Marcus

[Bassnut (Fred)]

Thanks Guys.

Mike S. Automated?, you mean the scope?, no, its my home rig.

Jase, bloody hell, there you go, I hadnt thought of useing different combines and merging them, you learn something every day. Rounding eggy stars isnt that hard in PS (double image size, move,halve size), its the poisson reject that screws them before you get to PS, but as you say, different combines mixed is an excellent plan. Yes,OK the stars stay. Its hard to plan useing the F/R or not on each image, given you need a new set of flats each change, and it can depend on how everything looks at the end (too late). The 3nm Ha needs huge exposures for the Lum channel, but is vastly better detail than the the RGB subs. Synth Lum from RGB would look awefull.

Hehe, thanks Alex, Mike and Marcus.

Steve, yes, its an awkward FOV for this elongated object, not wide enough for the whole thing (can go wider, that would mean the ED80, thats far too wide), and even at f10 not eough neb to fill the screen.

No, its not automated persay, apart from the obs closing (and mount switched off) automatically, which is actually a huge advantage on its own.

After totally manual set up, I just use imageing "sequence" in DL (no special software) and off it goes, sometimes for up to 5 hrs straight (no flip), and im inside watching TV or abusing ppl on IIS. When you think about it, cant every scope do that?, it just guides on the same object the whole time and takes frames, changing the filters sometimes. I dont understand why every one who has an obs doesnt do it, theres nothing to do all all while its imaging, easy. M17 was done from about 7pm to 10pm for several clear days, so I didnt need the "autoclose" (only for when it goes to 2-3am).

[leon]

I"m speechless, can't comment, its a bloody ripper Fred.

Leon

[Garyh]

Good one Fred!
I reckon the stars look pretty good in this.
I just love what you can do with all that Ha!
Very nice result!

[gregbradley]

Fabulous image Fred.

Great detail in showing some of the dimples and bumps in the nebula I haven't seen before and the neb is very smooth and solid looking.

You've got me thinking about buying a 12 inch LX200R. After all the noise about its not an RC its overshadowed its actual performance which is fabulous.

Do they work with large chip cameras? Do you know of a flattener that works with them? I bet my 4 inch Tak flattener would and I also have an RCOS flattener that almost for sure would.

Greg.

[Jen]

OMG Fred those pictures are amazing did you take all those other pictures on that web page too great stuff cheers

(jen wishes she could do that)

[Lester]

Fantastic image and goes to show that there is no replacement for length of exposure time.

[Deeno]

Glorious....
Fine detail

[Bassnut (Fred)]

Thanks again Guys.

I dunno about that Greg, id be keeping the RCOS if I were you ;-). I dont know how big a chip you can fit on a LX200R.

LOL, yes theyre all mine Jen, but some were taken with remote scopes.

[Jen]

Originally Posted by Bassnut

LOL, yes theyre all mine Jen, but some were taken with remote scopes.

GREAT WORK

[Bassnut (Fred)]

Geez, thanks Jen

Come to think of it Lester, youve got a potentially awesome rig/cam there, have you tried megadata?, with CCD stack and PS, you could do massive damage with that megapixel cam (I just love mega anything, it rocks ).