Rosette Nebula (NGC2237) combining two dual-band filters

[old_eyes]

Continuing experiments with dual band filters and colour camera.

Taken on Pier 5 @Roboscopes in Spain (Tak Epsilon 180, ASI 2400MC Pro, Askar Colour Magic Ha/O3 and S2/O3 filters, unguided paramount MX). 3hrs Ha/O3 and just under 5hrs S2/O3 in 120 sec subs.

Processed in Pixinsight. Filters processed in dividually and then combined using PixelMath expression - "Max(0.7*HaO3, S2O3)".

LocalHistogramEqualization used to emphasise the Bok globules. Cropped to about 75% of original.

Pleased with this one, but suggestions for improvements gratefully received.

[Stuart1971]

Looks superb…👏🏻👏🏻

the nebula is top notch, I like the colours too, corner stars a bit dodgy, especially top right, maybe run through the new BlurX version AI4

[Sp@ce_d]

Nicely done.. your data looks great but +1 for BlurX if you haven't tried it yet. I've not done any astro for ages but having tried BlurX out of curiosity on data I gave up on years ago it's got me fired up with enthusiasm again  😃

[old_eyes]

Hmm! Interesting. I tried BlurXterminator with AI4 instead of AI2, but it did not improve things. Closer examination shows that both filters show tiny ghost stars next to the brighter stars. These give the impression of out of shape stars, but are artifacts of the stacking process.

I don't understand than yet, but the seem to arise from misregistering of some frames in WBPP in Pixinsight. 

Needs more investigation!

[Stuart1971]

12 hours ago, old_eyes said:

Hmm! Interesting. I tried BlurXterminator with AI4 instead of AI2, but it did not improve things. Closer examination shows that both filters show tiny ghost stars next to the brighter stars. These give the impression of out of shape stars, but are artifacts of the stacking process.

I don't understand than yet, but the seem to arise from misregistering of some frames in WBPP in Pixinsight. 

Needs more investigation!

Those are artifacts from using BkurX on too higher sharpening settings…

[maw lod qan]

Excellent image!

[old_eyes]

5 hours ago, Stuart1971 said:

Those are artifacts from using BkurX on too higher sharpening settings…

OK. I will try some experiments with lower settings, but these 'artifacts' are found in the original linear data out of WBPP. They are fully separated from the major star for low brightness stars covering only a couple of pixels, but in brighter larger stars they look like a bump on the side. Not a classic egg shaped star, but a sense of a separate centre. I will upload some examples when I get a moment (currently WBPPing data from another run on the same pier. Those 35mm sensor files are big!).

[Stuart1971]

50 minutes ago, old_eyes said:

OK. I will try some experiments with lower settings, but these 'artifacts' are found in the original linear data out of WBPP. They are fully separated from the major star for low brightness stars covering only a couple of pixels, but in brighter larger stars they look like a bump on the side. Not a classic egg shaped star, but a sense of a separate centre. I will upload some examples when I get a moment (currently WBPPing data from another run on the same pier. Those 35mm sensor files are big!).

Interesting, i have some data with issues like that, so would be interested to get to the bottom, of it, as for now the new BlurX sorts it perfectly…

Look at these corner stars from a recent image of mine, they are like you describe, a main star and what looks like a small bump on the bottom right corners…it’s not easy to make out, but it’s there, if I have the star sharpening at the default of 0.5 in BlurX AI4 it shows it as two stars, a main one and a tiny one next to it, like yours were showing…

 

[old_eyes]

2 hours ago, Stuart1971 said:

Interesting, i have some data with issues like that, so would be interested to get to the bottom, of it, as for now the new BlurX sorts it perfectly…

Look at these corner stars from a recent image of mine, they are like you describe, a main star and what looks like a small bump on the bottom right corners…it’s not easy to make out, but it’s there, if I have the star sharpening at the default of 0.5 in BlurX AI4 it shows it as two stars, a main one and a tiny one next to it, like yours were showing…

 

What did you set star sharpening to to get the best result?

[Stuart1971]

Just now, old_eyes said:

What did you set star sharpening to to get the best result?

For me the new default of 0.5 was way to much, I found 0.25 to 0.35 about right, the default before the update was 0.25, so that’s a good start point….👍🏻

[old_eyes]

Here are the top right hand corners of the image straight from WBPP and then after DBE and BX.

Straight from WBPP. Only STF and Dynamic Crop applied

With DBE and BX.

The second centre is clearly visible in the data straight from WBPP and BX separates it into two stars.

But, the effect is even there in a single sub!

It must be something in the optics, unless we are getting a reproduceable jitter during a single 120 sec exposure?

So I don't think BX is going to help in this case

[Stuart1971]

36 minutes ago, old_eyes said:

Here are the top right hand corners of the image straight from WBPP and then after DBE and BX.

Straight from WBPP. Only STF and Dynamic Crop applied

With DBE and BX.

The second centre is clearly visible in the data straight from WBPP and BX separates it into two stars.

But, the effect is even there in a single sub!

It must be something in the optics, unless we are getting a reproduceable jitter during a single 120 sec exposure?

So I don't think BX is going to help in this case

Hmmm, yes yours is much more pronounced than mine…🤔🤔

[Clarkey]

On 17/12/2023 at 13:07, old_eyes said:

Pleased with this one, but suggestions for improvements gratefully received.

Great image in the nebula. Personally, I would put half an hour into RGB for the stars. I find this really helps with NB images.

Not sure if it related, but I have had a few issues with registration of Roboscopes data (P3 here). I do wonder if some of it is due to the very high humidity recently, causing some fat stars on certain nights. Probably unrelated but blinking through some of images has really shown the variation.