17 replies to this topic

[pyrasanth]

Having completed the M81 image I thought it was time to go and pick on a few of its colleagues. Last night was clear however the moon was full so this meant narrow band imaging on the C14.

 

I'm really fortunate to have a filter wheel loaded with LRGB and narrow band 50 mm filters- so that saves lots of time.

 

I had a little bit of data saved from a previous session so I added a further 12 hours of HA data bringing this integration to 183 x 5 minute subs or just over 15 hours on a 3x3 bin using the ASI6200 and Baader 3.5nm enforced HA filter. This is about 0.84 arc secs per pixel and grabbed a lot of detail.

 

As previously commented on in other posts long subs are no good to capture faint wispy data- you need lots of relatively short subs, at least for narrowband where short is 5 minutes or under for my C14.

 

I would guess I need another 15-20 hours of HA data to break out the really fine detail. I may then use the HA image as a luminance sub for the RGB when I start on that.

 

As always comments invited on this initial HA master as a work in progress.

 

Clear skies to you all.

 

Edited by pyrasanth, 18 January 2022 - 11:21 AM.

[Mert]

In 1 word: WOW
Great detail

[pyrasanth]

Thanks Mert- the weather is quite good currently so I'm capturing more data tonight. It is forecast to be clear tomorrow as well so I might get all the HA between tonight and tomorrow- I'm looking for around 25 hours plus.

[happylimpet]

Great minds! Seemed like a sensible target being so high eh. The moon still kills h alpha as much as broadband, its just that h alpha starts from a much more contrasty standpoint.

 

I just managed to squeeze M81 and M82 into the FOV, but the stars a little wonky in the corner with M82.

 

Ive got 11 hours here with a 16", which I suppose works out about the same as your 15 hours with a 14". But you seem to have better SNR, so maybe thats down to the 3.5nm filter cf my 7nm.

 

 

[pyrasanth]

I continue to capture the HA data for the M82 image that I'm building. It's taken 20 hours of data so far to begin to fill out the loop in the image of HA data.

 

I found some of the background processing modules far too aggressive on this data. The signal being faint was being misinterpreted as noise and getting removed.

 

I used masking techniques using MLT to transform the mask edges to make them much more feathered thus being able to blend background correction around the M82 image structure in a far nicer way.

 

I resisted the temptation to denoise the HA loop- I want to really see this data naturally get smooth through data capture to get a better idea as to its structure and not merge pixels with noise reduction.

 

I hope to be able to complete the data collection tonight and with the offer of Nick (HappyLimpet) to be able to incorporate his data into my set we should get a very nice M82 HA frame for subsequent use.

 

As always comments invited. The removal background techniques work great on HA data as your not getting too much background to worry about. It might not be suitable for nebulous fields however it serves this image purpose quite well.

 

Edited by pyrasanth, 19 January 2022 - 08:49 AM.

[chrysalis]

I continue to capture the HA data for the M82 image that I'm building. It's taken 20 hours of data so far to begin to fill out the loop in the image of HA data.

 

I found some of the background processing modules far too aggressive on this data. The signal being faint was being misinterpreted as noise and getting removed.

 

I used masking techniques using MLT to transform the mask edges to make them much more feathered thus being able to blend background correction around the M82 image structure in a far nicer way.

 

I resisted the temptation to denoise the HA loop- I want to really see this data naturally get smooth through data capture to get a better idea as to its structure and not merge pixels with noise reduction.

 

I hope to be able to complete the data collection tonight and with the offer of Nick (HappyLimpet) to be able to incorporate his data into my set we should get a very nice M82 HA frame for subsequent use.

 

As always comments invited. The removal background techniques work great on HA data as your not getting too much background to worry about. It might not be suitable for nebulous fields however it serves this image purpose quite well.

 

M82_HA_CN.jpg

Beautiful "retro" image !!

[Look at the sky 101]

Wow superb shot. 

[raguramm]

How does it look without any background manipulation? To me the BG looks a bit plasticky and the noise transition from background to DSO is harsh. I’d be interested in seeing a plain histo-transform.

[pyrasanth]

How does it look without any background manipulation? To me the BG looks a bit plasticky and the noise transition from background to DSO is harsh. I’d be interested in seeing a plain histo-transform.

Thanks for your observations. It is very easy to "inject" poisson noise into the background to remove that plastic feel. The transistion between the object and the background can be controlled by not using as many iterations of MLT. This is not so important for a HA image where only the Galaxy will be used to add into an LRGB composition. I agree as a standalone HA image it needs to have a bit more to look at in the background. I only wanted to illustrate that on some targets background removal can work well. I image under Bortle 7 sky so it takes a lot of subs to get a background which is very nice even with good calibration.

[zoran]

Very interesting image!

The level of detail visible is truly amazing!

Zoran

[pyrasanth]

I'm working on an image of M82. I wanted to get a feel as to how the HA data would sit as a Luminance layer on the RGB data.

 

The image presented is only 4 hours of RGB with 21 hours of HA data dropped on the top.

 

It has very little processing only a quick saturation tweak in photoshop.

 

I think my focus will be on a bit more RGB data however I will carry on and max the HA data as much as I can. The image feel is giving me what I'm looking for and should be great when actually processed.

 

I plan to drizzle the data- I'm undecided where the natural L data that I've captured can be placed- its a shame to waste it however I'm not very successful at HALRGB integration yet- so still learning about that process.

 

Comments as always gratefully invited.

 

Clear skies to you all.

 

Edited by pyrasanth, 20 January 2022 - 11:12 AM.

[imtl]

Very nice!

[afryhover]

I've begun using Ha data as Luminance data also. It sure helps keep the stars smaller while getting the details we're after. Looking good.

[pyrasanth]

The HA data capture is complete. I stopped at 28 hours which filled out the missing HA data regions nicely.

 

I have 2 hours through each filter of RGB data and about 3 hours of L which has not been added to the image. The L data is still quite noisy so I will await the next clear moonless night to finish capturing more L data. I've built the image using the NBRGB Combination module in PI- this made the HA integration pretty painless when used with care.

 

A larger image is here https://www.astrobin.com/e1ld9o/

 

As always comments invited with the RGB data there is 34 hours of integration into the image so far.

 

[galacticinsomnia]

The HA data capture is complete. I stopped at 28 hours which filled out the missing HA data regions nicely.

 

I have 2 hours through each filter of RGB data and about 3 hours of L which has not been added to the image. The L data is still quite noisy so I will await the next clear moonless night to finish capturing more L data. I've built the image using the NBRGB Combination module in PI- this made the HA integration pretty painless when used with care.

 

A larger image is here https://www.astrobin.com/e1ld9o/

 

As always comments invited with the RGB data there is 34 hours of integration into the image so far.

 

M82_NBRGBCombination_RGB_FLIPPED.jpg

That is looking really nice..  I love it !

The only thing to me that I can see, is the desire for more sky and star color.  Regardless of that, that is a really nice work.

Clear Skies !!

[pyrasanth]

That is looking really nice..  I love it !

The only thing to me that I can see, is the desire for more sky and star color.  Regardless of that, that is a really nice work.

Clear Skies !!

The Sky and stars will be better when I add the Ldata however I now need lot of L data to light up the image.

[pyrasanth]

I've added some colour to the stars by using an Arcsinh stretch on the stars. I still don't have enough L data to be happy with the background quality. I await the next night to capture more.

 

Here is the brighter star image https://www.astrobin.com/e1ld9o/C/

Edited by pyrasanth, 23 January 2022 - 08:49 AM.

[pyrasanth]

I've added the first set of L data to the image- it's only 3 hours so is a bit noisy so I can't lift the background yet without damaging the original posted image. However the L data is filling out the image as M82 looks wider at the boundaries.

 

Edited by pyrasanth, 23 January 2022 - 01:27 PM.