NGC6188 Fighting Dragons

[Craig_]

My first step away from the beginners forum with this one. Feel free to send me right back :lol:

I've re-processed this image probably a dozen times since capturing the data over two nights last month. At five hours in total this was my longest integration yet (and yet still nowhere near enough for this target.) Initially I had processed it with a lot of reds, but wanted to try and emulate the SHO palette as best I could without any Sii data, as this was taken on an OSC.

Fairly happy with how it's turned out although I think next time I manage to find myself out of Sydney with the gear (need some decent weather:shrug:) I'd like to spend more time on it. Some Sii data would be nice too but probably a fools errand on this target with an OSC, sadly.

ASI533MC
EQ6-R
Esprit 80
Optolong L-Enhance filter

Stacked and colour-combined in APP, processed in Photoshop.

[Ryderscope]

That image stacks up Craig and definitely worthy of display. It would be good if you could find a hosting platform (Flickr, Pbase, Astrobin etc.) to make high res versions available so we can see them in all their grandeur :) The emulation of SHO has come out well so a good result in all :thumbsup:

[Craig_]

Thanks! I have chucked a higher res version on my sparsely-used Flickr page here: https://flic.kr/p/2jw7Dyi

[Atmos]

Good detail and nicely resolved :) The colours do look good, you'll never get an accurate SHO colour palette but you've done well to get close with just the Ha and OIII emissions :thumbsup:

[Placidus]

The Ha and OIII data are looking very fine. Well done. :thumbsup::thumbsup::thumbsup:



[ominous sounds of Mike getting up onto his High Horse]


The purpose of the SII is not to put red in the image, nor to stop it being green, nor to get a certain look. It is to find areas of recent ejection of star guts, most commonly in the form of a huge supernova remnant, but also from Wolf Rayet nebulas, and at the smallest scale, from planetary nebulas.


It is completely impossible to even begin to guess what the SII might look like from the OIII and H-alpha alone. Therefore, it should not be attempted.


[Happy sounds of Mike dismounting from High Horse].


You're already romping ahead there. Do get yourself an SII filter. Places where you'll quickly get results:


- Tarantula nebula
- Gabriela Mistral Nebula.


Both these show glorious SII emisision, well localized and separate from the general H-alpha.



The Chalice Nebula has a beautiful SNR and other features which only shows up in SII, but it is much more difficult. Just about any other super-violent region in the LMC and SMC, and any supernova remnant at all will show discretely localized SII, but don't start with those.



Thor's Helmet and Norma Bipolar Nebula are good examples of WR nebulas with good SII, the mechansim being entirely different from past supernova activity. The stuff is spewing out of a huge hot star right now, long before the explosion.


Another good one is the Dumbell nebula, a planetary nebula which looks quite different in SII. Again, the mechanism is completely different from the previous two. A much smaller more sun-like star has lost its atmosphere, but enough SII has been dredged up and blown off the beyond white-hot core for us to see.




Total waste of time are gentle star-forming regions where nothing much extra-violent has happened yet:



- Trifid nebula, Running Chicken. Not so much SII to be found, and what there is tends to be co-localized with H-alpha. That is of itself of great interest, but not one to practice on.


Anyways, welcome to broadband and keep up the superb work!


Best,
MnT

[Craig_]

Thanks :)



Thanks for the comments and wealth of insight on Sii :) I guess the reason I don’t already have one is that Sii has a rep for being a fairly weak emission on most objects and given with an OSC I’d only be using 25% of the pixels to gather Sii data, I imagine I’d need very long subs and a large amount of total integration to gather anything useful in all but the richest Sii objects? Ha being much more prominent (typically) seems viable with an OSC despite the same limitations of it only hitting 25% of your pixels. Maybe someone needs to develop an Sii and Oiii dual band pass filter in the same vein as the plethora of Ha and Oiii ones - at least then I could be gathering more Oiii data at the same time :lol:

I’m really looking forward to imaging Tarantula Nebula actually and just ordered a bigger OTA (Esprit 120) which should do nicely on that object when it’s a bit higher in the sky. A mono camera is on my wish list but I don’t have much interest in the tiny pixels of the 183MM and the 1600MM whilst a workhorse for many, I feel a bit ripped off paying $2000 for something with such an old sensor (12 bit ADC, micro lens diffraction issues etc.) A 6200MM would be a dream but a bit much I think... I’ve been really really impressed with the 533MC sensor but OSC certainly has its limitations.

[Placidus]

Spot on. It's a bit like hunting for truffles. One needs to be seriously addicted for it to be worth the effort. We've got 20 inches of aperture and a 16 bit CCD mono camera, but we still need to throw a full night of half-hour subs at the SII, often 2x2 binned (which latter doesn't apply to ZWO cameras where it won't help).

Lately we've realized how beautiful galaxies are, even how beautiful globular and open clusters can be, if you're really careful with the colour. Perhaps we're starting to lose the narrowband/SII faith.