Forever Chasing the Flux

[Catanonia]

Since I started this hobby, quit and restarted again, I have always been chasing the IFN (flux) around the Bodes Galaxies (M82 / M81)

I tried many years ago with a Skywatcher MN190, then with a Boren Simon F2.8 Newtonian, but never got the results I wanted. 

I was beginning to think that it was not possible in the skies (bortle 6) that I had.

Fast forward to this year and new kit, it was time to try again, this time with a Rasa8 and ASI 2600 MC Pro.

I think I cracked it at long last  !!!!!!

Bodes Flux from Bortle 6 South Cheshire

• Rasa 8 with ZWO 2600 MC Pro
• NEQ6 Pro Mount
• 138x 2min subs at bin 1
• Darks, flats etc etc
• And 98% processed in PixInsight with only Photoshop for final level and black border.
• PI work was using EZDenoise, a few masks, Histograph, Curve and a little LHE processing. I processed the Galaxies and IFN in separate images and then combined them.

Still a lot to learn in the processing as trying to extract the IFN leads to noise that is hard (for me) to control.

Would love your C & C's on this one as like I said, so much more to learn, especially around the processing of dust lanes.

TIFF and JPG below

FInal Combined.tif

Edited January 9, 2022 by Catanonia

[vlaiv]

IFN is all about SNR.

You should consider binning data that you already have - say even x4 in order to keep noise down.

In the end good denoising routine will help smooth things.

 

[Catanonia]

8 minutes ago, vlaiv said:

IFN is all about SNR.

You should consider binning data that you already have - say even x4 in order to keep noise down.

In the end good denoising routine will help smooth things.

 

mmm, I could try that next time, 1 set of data for the IFN at 4x bin and use what I have now for the actual galaxies.

Might try and see if I can 4x bin the existing data for the IFN and see what happens. Will of course mean I will end up with a 1/4 sized image, but that should not be a problem with the size of the 2600 chip.

Thanks for the C&C, appreciated.

[vlaiv]

Just now, Catanonia said:

Might try and see if I can 4x bin the existing data for the IFN and see what happens. Will of course mean I will end up with a 1/4 sized image, but that should not be a problem with the size of the 2600 chip.

You can just bin linear data that you now have.

Mind you - you won't end up with smaller image when viewed on computer or phone screens - unless zoomed in. Posted on SGL for example - it will look the same as image itself is scaled to fit the page.

Btw - you are a bit over sampled as is and you need at least bin x2 to get to appropriate resolution.

See star sizes and galaxy? That does not look very sharp when viewed at 100% zoom.

[Catanonia]

9 minutes ago, vlaiv said:

You can just bin linear data that you now have.

Mind you - you won't end up with smaller image when viewed on computer or phone screens - unless zoomed in. Posted on SGL for example - it will look the same as image itself is scaled to fit the page.

Btw - you are a bit over sampled as is and you need at least bin x2 to get to appropriate resolution.

See star sizes and galaxy? That does not look very sharp when viewed at 100% zoom.

mmm, will have to look at this. Was 2mins at 1x bin on the Rasa8 and 2600 MC Pro.  Is there anyway to measure what I should be and what I am ?

 

[vlaiv]

4 minutes ago, Catanonia said:

Is there anyway to measure what I should be and what I am ?

As far as resolution?

Sure - measure average FWHM. It should be ~1.6px. If it is larger than that - factor of two values will give you how many "times" you oversampled. Say you measure FWHM of 3.2px then you oversampled by 3.2/1.6 = x2 and you should bin x2 to get proper sampling rate (I just used numbers that give convenient result - but it's never that "easy"   - usually you get some "random" value like 2.4px so factor is 2.4/1.6 = 1.5 and there is no easy way to bin x1.5 as binning is integer operation).

If you are chasing IFN however - round it up to nearest higher number say you get x3.4 - then bin x4 or if you get x1.5 then bin x2 (or even higher for IFN).

[Catanonia]

7 minutes ago, vlaiv said:

As far as resolution?

Sure - measure average FWHM. It should be ~1.6px. If it is larger than that - factor of two values will give you how many "times" you oversampled. Say you measure FWHM of 3.2px then you oversampled by 3.2/1.6 = x2 and you should bin x2 to get proper sampling rate (I just used numbers that give convenient result - but it's never that "easy"   - usually you get some "random" value like 2.4px so factor is 2.4/1.6 = 1.5 and there is no easy way to bin x1.5 as binning is integer operation).

If you are chasing IFN however - round it up to nearest higher number say you get x3.4 - then bin x4 or if you get x1.5 then bin x2 (or even higher for IFN).

thanks vlaiv, will look into this and do some measuring