Trifid in Narrowband

[codemonkey]

A relatively short Trifid, only 3.2hrs of narrowband data. Seeing has been pretty average here and I kept subs at 150s to try and get more keepers. Still I've thrown out about half the data, and most of what I've kept is on the worse end of what I'd normally consider keeping.

Full res (same crop) available on Astrobin (http://www.astrobin.com/256915/).

[atalas]

Yep the seeing has been crap down my way too the last couple of days ...good effort though Lee!

[codemonkey]

Thanks Louie! Tonight is supposed to be better, apparently, so I'll go back to trying to image a medium sized galaxy and hopefully I can get some nice data on that. Hope the seeing improves down your way too.

[atalas]

Lee,If the seeing doesn't behave you might be better off shooting 2x2 and then at least the S/N would be much better.

Anyway looking forward to more reuslts....still thinking about this cam.

[codemonkey]

Cheers mate. Normally a good call, but binning the ASI 1600 drops it down to 10 bits, and I get the impression it's basically only useful if you want to speed up file download (e.g. for planetary).

I think when you get down to this sort of read noise there's probably not much advantage in hardware binning anyway though, so there's that too.

I'm still figuring out this camera and how to get the best out of it.

[glend]

Lee i would not bother with binning at your focal length. Nothing wrong with 150" subs just shoot twice as many.;)
Tis the week for broadband now. You have no doubt seen Ray's NGC6727 image, which sets a benchmark for us all. The Helix Nebula is also high enough to image from about 11pm. I am shooting both those this week.

[RickS]

Looks pretty good, Lee. You got one of the jets quite clearly.

Cheers,
Rick.

[strongmanmike]

Funny, when I saw this post I though, meah not much chop probably, Trifid never looks any good in NB :rolleyes:...well, then I opened it in Astrobin and well, sheesh, looky at that :eyepop:...looks pretty good! Shame about the seeing, if that had been better t'would have looked most very excellenter :)

Mike

[Atmos]

Looking good Lee! Have you mapped it in HSO?
It appears to have done really well with 150s subs, what gain did you use for such short NB subs?

[codemonkey]

Nyeh, 150s with OIII has read noise at about 23% of background with my skies, so it's not ideal.

I'm looking forward to having a good crack at the Helix, but it'll be a while yet for me... I have to get up at 6 for work and need all the beauty sleep I can get!



Thanks Rick :-) I think I can make out two.



haha yeah. When I started this one it was perfectly placed for the time I wanted to start imaging, but the moon was out and about. I didn't recall seeing a NB trifid that I liked, and didn't expect much from it to be honest. I ended up with a palette that brings it closer to its broadband appearance which is probably why it's a bit more palatable.



Cheers Colin :-) I ended up with the following mix:

R = Ha
B = O*.3 + S*.7
G = S*.3 + O*.7

I used unity gain. I think at this point I'll pretty much stick with unity unless I find a good reason not to.

This one also has pretty heavy noise reduction. You can notice it especially around some of the stars where they start to look a bit milky for lack of a better term.

[Atmos]

Didn't want to mention it with the stars :P It actually looks like the nebulosity has been stretched or meddled with while the stars are masked.

[gregbradley]

Its reasonably detailed for bad seeing. Short exposures may not have been the way to go as the longer subs would take more sharpening.

I like the colour you've gotten. The image could improve with some selective sharpening and some RGB stars.

But for my taste the feature of the Trifid that I find the most beautiful is the magic blue reflection nebula that surrounds the lovely reddy pink main nebula.

Narrowband does not show that lovely blue as its not O111 but reflection off of dust. So I personally always prefer HaLRGB versions of this object.

The hard part of this object always seems to be the background stars as there are black dust areas that seem to interfere with the stars and widefields of this area show a sea of golden stars as you are near the centre of the Milky Way here.

Greg.

[codemonkey]

Thanks Greg, appreciate the constructive criticism, all very good points! I've now gathered LRGB data, and applied deconvolution to the super luminance, which I'll post up in a separate thread.

[marc4darkskies]

Nup - afraid I don't like this palette Lee. As I get into pure NB myself, I prefer seeing the SHO palette. Sure, SHO doesn't look "natural" at all but that's the point. Purely personal taste of course.

[gregbradley]

For me the reference image for a narrowband version of the Trifid is Martin Pugh's image of several years ago.

Greg.

[codemonkey]

All good Marcus, looking back on it after doing the version with LRGB, I'm not a huge fan either. Appreciate the honesty!



Holy sh*t, I just looked that up... that is amazing.