Ngc 6334

[Slawomir]

Hi all,

Just sharing the fruits of my attempt at the Cat's Paw Nebula.

Data collected over several nights from Paddington in Brisbane and adding up to exactly 19 hours of integration.

Data from Ha, S2 and O3 Astrodon's 3nm filters was blended to create the final image.

Any feedback, suggestions and even rotten tomatoes will be appreciated and valued.

Large version: http://www.astrobin.com/full/201490/0/

Full resolution: http://www.astrobin.com/full/201490/0/?real=&mod=

S.

EDIT: new full resolution: http://www.astrobin.com/full/201490/C/?real=&mod=

[Octane]

Crikey, that is astounding!

Do a starless version? :)

H

[Placidus]

Slawomir, that's absolutely superb. Extremely sharp, fine tracery of dust lanes. No hint of sharpening artifact. Beautifully processed.

It might be possible to wring a tiny bit more OIII out of it, but there's very little there, and the way you've presented it is true to the object.

Well done.

[Rod771]

Well, you must be pleased with that result Slawomir.

Great work! :thumbsup:

[Somnium]

Beautiful NB image. well done, you have to be happy with that

[Paul Haese]

That is an interesting take on this object. I really like the feathery detail in the full res image and there is a very minor amount of speckle in the back ground. The full res does look just slightly blurred, but the detail level is more interesting. The large resolution image looks very sharp and I think a better way to show the image. The colour contrasts seem nice in the smaller presentation. Well done. I like it.

[Regulus]

That's wonderful Slawomir, superb photo.

Trevor

[strongmanmike]

Really nice Slaw, lovely fine details that are the hallmark of good NB images and the framing gives it a rather dynamic look, like it is a large creature changing direction under water, perhaps a big jelly fish or giant squid. The colours are vibrant and fiery too, very Rickesque there ...ready to print straight onto metal or glass I recon :thumbsup:

Mike

[DavidTrap]

Noice - one for the to-do list!

DT

[codemonkey]

Dude, that's awesome. Only thing that could make it better imo is more data, which of course always makes things better ;-)

[Slawomir]

Thank you all for your very kind feedback. The truth is I did not expect that I will manage to "paint" this nebula with different colours - it is very strong in Ha, has decent S2 but it turned out there was very little signal in O3.

It is not as sharp as I would like; there was some backlash in the mount in both axes (now I have eliminated it) and on a few occasions dew started forming on the lens - I will need to get dew controller and a heater...

I was hoping to collect more data but some people of this forum (not pointing fingers at anyone in particular...) have been recently buying telescopes and good weather has ended ;)

Starless version? Hmmm, for some strange reason I actually do not like very much starless images of the nightsky, as they seem to me to be hollow and dead.

Instead of removing stars, I have corrected colours a tiny bit - there were some subtle gradients that I did not like...I recon it will have to go on aluminium! :lol:

http://www.astrobin.com/full/201490/B/

[jase]

A stunning image Slawomir. :thumbsup: One of your best in my opinion. Presents a pleasing balance of emission lines. They are distinct enough to get an ideal of the nebula characteristics and just as important, look aesthetic.

[Atmos]

When I first just looked at the thumbnail it was a "wow" moment, very well captured.

[rat156]

It's a beauty, this was next on my list of images to take, now unnecessary. I really like the colours. Congrats on a fine image.

Cheers
Stuart

[Andy01]

Thats a crackerjack image Slaw.
Bloody hard target in NB (I know, I tried, got over 12hrs data and was still unhappy: gave up...)
Very well done, you have done a stellar job on this, possibly a benchmark for NB on this one. :thumbsup:

Andy

[rustigsmed]

yep, awesome work. i like it a lot, well done!

Rusty

[MGTechDVP]

That looks great... nice to see it in a different color spectrum.. there is not many narrowband versions of the Cat's Paw.

[kkara4]

Sensational Slawomir! especially from right near the middle of BNE!

[topheart]

Very well done!

Congrats,
Tim

[lazjen]

That's a great image. I'll have to have a go at this target in NB too sometime, probably next year. :)

[gregbradley]

Wow Slawomir that's a stunner. Its very vivid and clear. Very real. Amazing.

Greg.

[Slawomir]

Thank you gents for your very kind words of encouragement - your feedback really means a lot to me.

Now the questions is...should I get the scope out and collect more data for this image? It's a clear night and new moon... :)

[codemonkey]

lol. How inconsiderate of them.



I reckon you could smooth some of the fainter signal out with a little bit more data, but whether it's worth the effort is up to you; more data is always nice but there's a point you reach when you'd rather go image something else.

On the other hand, if there's nothing else capturing your fancy right now, then why not?

[Slawomir]

Thanks Lee,

I decided to take advantage of clear skies tonight and collecting more Ha data for this nebula. Maybe tomorrow night we will be lucky again here in Brissie and I will add the last 2 or so hours to Ha.

Anyway, it looks like I managed to eliminate most of backlash - SGP has put the scope right on the target on the first attempt to within 3 pixels twice already- at the beginning of the session and after meridian flip. Currently guiding is as good as I ever got with AZ-EQ6.

[DJT]

That's an excellent image. I hane not seen this in NB before and it works a treat. The fact that there isn't much Oiii means that what there is is very subtle in the overall scheme of things and it comes across just right.

Top job:thumbsup:

[Rex]

Beautiful image Slawomir, and a different take on a fairly common object. Love the warm colour palette. Outstanding!

[Slawomir]

Thank you David. Yes, there was very little O3 and thus it required some work to get reasonable signal out of it.



Glad you like it Rex :)

[codemonkey]

Awesome! Looking like another clear one tonight, at least up in my neck of the woods so you should be about to get those last couple of hours.

[Slawomir]

Added another 4.5 hours, bringing the total integration time to 23.5 hours.

Noise in the background went down by about 10%. I only applied very soft noise reduction, as I prefer noisier images that preserve detail over smooth and overcorrected.

I think I am happy with the current result and will probably leave it as is.

Large image: http://www.astrobin.com/full/201490/C/
Full resolution: http://www.astrobin.com/full/201490/C/?real=&mod=

Thank you for looking.

Slawomir

[Paul Haese]

I like that even more now Slawomir. Colour is a bit richer now too. If you have not already, you should submit for APOD. This is a fairly unique looking image and might just grab their eye.

With regard to noise. I have found that no noise control is necessary after a certain amount of time in each filter. It depends on the object. Some objects require more data than others. Obviously the brighter the object the less data required to over whelm the noise. Although some objects such as dark nebula require deeper exposure even if they are close to a bright object. In your full res now the noise level is extremely low (like a very mild fuzz if anything) and not worth going any further in my opinion.

A bench mark image now of this object. Until now I would not have considered doing an NB image of this object. Excellent work.

[codemonkey]

Nailed it, S! That extra bit of data turned an awesome image into something, well, even more awesome. As Paul says, you've just set the benchmark.

[Slawomir]

Thank you Paul very much for your feedback.

I tend to get more noise due to my location (heavy light pollution), so I usually try to apply a tiny bit of noise reduction, aiming for the background areas. I used to overdo noise reduction in the past...

Out of curiosity, and because I like simple graphs and basic maths, I integrated different number of calibrated Ha subs from this project and compared standard deviation for the same area for all of them. I picked a uniform patch of the image that represents background only. (see the attached graph).

Interestingly, equation that fits the trend line is pretty much spot on with what one would theoretically expect...St.Dev being inversely proportional to the square root of the number of subs. :)

The equation: Noise (st.dev.) = 50 / sqrt (n)

or generally: Noise (St.dev) = noise_in_one_sub / sqrt (n)

Might be a useful tool for roughly estimating noise at the beginning of a project and helping to decide/plan on the amount of integration...maybe.



Thank you Lee. It was your suggestion that prompted me to get a bit more data... :)

[Regulus]

What Paul said :-)
And I'll add: excellent apparent depth

Trev

[rat156]

Hi Paul,

Whilst I agree with the sentiment of your post, I have to go all English Nazi on you and point out that nothing is "fairly unique", it's either unique, or not. Having said that, aren't all of the images here unique?

Cheers
Stuart

[Atmos]

That is a very nicely looking Paw, like a cat has run over some hot coals :P

[multiweb]

The high res is superb. Awesome details. Looks very fiery like an explosion. Top shot. :thumbsup::thumbsup::thumbsup:

[gregbradley]

That's an interesting post Slawomir. So the bulk of the noise drop is done by the first 0 or 5 subs and then its a much slower rate of improvement and by the time you've done 50 you are not going to see much better by doing more at increasingly more work and time.

I wonder what optimum is then between weather, setup speed, work, object location, equipment foibles.

8 to 20 hours on a faster system and 20-30 for a slower system? Depending on the object's brightness and whether its LRGB or narrowband.

Greg.

[Slawomir]

Thank you Trevor!



Please do not pick on me... ;)



Thank you Colin, I am glad you like the colours.



Thank you Marc. Took some time to get there (11 evening sessions) :)



Agreed. There are many variables affecting the final image, so it might just serve as a rough guide. I think if one is after really faint detail, then perhaps every good sub would count. But it looks like for my setup and in my location and with my current skills, going over 25 hours with 3nm filters would be an overkill for majority of targets.

[Slawomir]

Interesting picture of the day (19 August) in the Astronomy Magazine... ;)

http://www.astronomy.com/tags/nebulae

[DJScotty]

Nice work. Totally worthy

[codemonkey]

Congrats S!

[RobC]

That's superb. Well done.

Rob

[RickS]

A fantastic Cat's Paw, Slawomir! Nicely captured and expertly processed. Congrats on the Astronomy POD too.

Cheers,
Rick.

[Slawomir]

Thank you gents :)

I could not resist and got it printed on metal...

[RickS]

I must drop by and take a look, Slawomir! Unfortunately, I mostly walk to work these days and rarely have a car during the day.

[Slawomir]

No problemo Rick, I keep only two prints at the restaurant - in the end it is a Thai restaurant, not a real venue for astrophotos :)

[Bassnut]

Wow, thats fantastic, very dynamic processing, a firestorm!. Looks especially good on a 4k monitor full screen !.

[gvanhau]

Bravo!! This one of the best I've seen on this object.

[Slawomir]

Thank you Fred and Geert, I am glad you like it :thanks:

One day I will get one of those 4k monitors...

[Bassnut]

Im now processing NGC6334 ive done myself, and your rendition has become somewhat the best reference I can find for my processing. Your a dark horse Slawomir, there is more to your effort than meets the eye. You have nailed "modified hubble" IMO and have upped the bar forceing me to change the way I process NB entirely, ive spent days on relearning processing in PS in many ways to avoid the failures of standard hubble and come close to your effort. Did you process only in PI?. I think you are right up with contempary processing and thank you for kicking my ass.

[gregbradley]

I wouldn't mind some tips as well. I have data on this to process from wide field to narrow field. Both in narrowband.

Some up to date tips would be good as that is an excellent rendition. I have been using the Astrodon screen mode Photoshop method as per Astrodon website. Its not bad. Not sure it would produce those sorts of electric colours though.

Greg.

[Slawomir]

Thank you Fred...honestly, I do not know what to say... I think you are way too kind :)

I processed the image entirely in PI, except for some experimental stretching with FITS Liberator.

I think it took me at least as much computer time to process the data as the integration time for this photo - clearly I need a faster computer :lol:



Thank you Greg, I will write a few humble tips sometime tomorrow, or the following day at the latest.

[codemonkey]

Fred's on the money mate, you're just too modest!

[Geoff45]

Very nice Slawomir. You've taken a Ho-Hum run of the mill nebula and turned it into a superb work of art.
Geoff

[Slawomir]

Thank you gents very much for your kind words and encouragement.

I was thinking of the tips that Greg has asked about, but not sure what would be useful.

Perhaps at the core of processing was extracting tone maps, such tone maps allowed for more freedom in achieving desirable colours in the final image. This tutorial explains how to create such masks: http://www.arciereceleste.it/articoli/translations/75-narrowband-color-composition-eng

Also I have learnt to be very careful and gentle with noise reduction, local contrast enhancement, sharpening and in fact any step - I feel that too often I used to "distort data" too much somewhere in process thus creating a monstrosity rather than preserving and bringing up the most subtle structures and presenting them in unison with brighter parts of a nebula.

[Slawomir]

Attached are Ha, OIII and SII jpgs (in that order) of original files for reference.

Each is about 8 hours of exposure.

[codemonkey]

Thanks for that S! I've been planning on displaying those for future NB work; it can be helpful to those who've not imaged a particular subject before in terms of deciding what to bother with.

[AlexN]

That is sensational. In every conceivable way.

Have you considered submitting that to APOD?

[Slawomir]

I have seen some people posting such previews, and I think it could be a nice practice for the reasons you have mentioned :)



Thank you Alex :)

APOD - what is it? Alternative Place Of Detention? ;)

[AlexN]

;)

[GC - South Aus]

:eyepop: Wow - Just.... Wow!

Regards :thumbsup:

Gav

[Slawomir]

Thank you Gav, glad you like it :)