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M31 - ASI1600MM - LRGB - 5hrs

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Guest

This imaging session, occurring over 2 nights was not without its mistakes and confusion! 

Setting up the first night I seemed to spend most my time trying to remember how to configure the capture software correctly.

y4mxe-BuddPpc66IK65Cm-IXy1Yw50VyFWs1nVwm

The second night I decided not to connect the guide camera to the PhD Guiding 2 correctly and spent 30 minutes establishing that fact.

However, out of the jaws of chaos (which extended to the processing of the image) came one of my better efforts on this object. It’s also the largest amount of data I’ve collected with almost 5hrs going into the can for processing.

y4m8FYgeR5tW8DQhAFS8Oys9C46YnTz0DAfGvaIS

 

 

Details

Object name

Andromeda Galaxy

Object ID

M31

Date(s)

11 and 12 October, 2017

Telescope

Altair 115mm

Camera

ASI1600MM

Luminance

89 x 2 min = 178 min or 2.96 hrs

Red

16 x 2 min = 32 min

Green

21 x 2 min = 42 min

Blue

19 x 2 min = 38 min

Ha

0

Oiii

0

Sii

0

Total time

4.8 hrs

Frames

0

Processing

PixInsight / Bias, Flats, Darks / Masked Stretch / Curves / ATWT

 

I’m having fun zooming in to the different parts of the galaxy to view the H2 regions (star forming) that I was quite surprised to have caught in such numbers. These regions, swimming amongst the sea of big, hot blue stars destined to burn out quickly, are similar to our own Orion Nebula. Moving to the core of the galaxy and it super massive black hole the cooler, longer lived red stars dominate.

y4mN2Wkp5iN0nncmlP0u55gRjQncLZ_5wUr5_BYv

Up to the left M110, another galaxy bound to Andromeda has resolved quite well – it can off look very pixelated – and nearby the big blue star who’s name I cannot find 

y4mjuJ3W4KREl-mVki8YOUvklTNmpuTGFW60_mzF

This galaxy is 220,000 light years across and contains a trillion stars which is twice as many as in our Milky Way galaxy.

I think I now need a lot more colour data for this but its a start.

David

 

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as a matter of interest what gain and offset are you using? I'm battling with M31 at the moment with the ZWO1600 and cannot get the right balance between exposure time gain and offset.

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Great job here Dave in spite of your troubles. I enjoyed the read too thanks. Will you grab some ha?

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Guest
54 minutes ago, Allinthehead said:

Great job here Dave in spite of your troubles. I enjoyed the read too thanks. Will you grab some ha?

That's a great idea - I actually didn't think of that - thank you ☺

David

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Guest
1 hour ago, groberts said:

as a matter of interest what gain and offset are you using? I'm battling with M31 at the moment with the ZWO1600 and cannot get the right balance between exposure time gain and offset.

I'm using unity gain at 139 and offset of 10 and haven't changed it for any of the images in my gallery on my website so far. Hope that is of some use - please don't hesitate to contact me if I can help further.

David

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2 minutes ago, David_L said:

That's a great idea - I actually didn't think of that - thank you ☺

David

I'd imagine you wouldn't need a huge amount either as you'd only be blending in the high signal areas. 

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Thanks for the offer, will see how things go - the problem is Luminance which seems to be blowing out even at low gain and short exposures. 

I have some M31 data from Thursday I need to process first.

Graham

 

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Guest
1 hour ago, groberts said:

Thanks for the offer, will see how things go - the problem is Luminance which seems to be blowing out even at low gain and short exposures. 

I have some M31 data from Thursday I need to process first.

Graham

 

At the risk of doubting your processing methods I have to note that I had a problem with the core in Luminance when adjusting levels in white point - when I did it with mid tones it was great. Hope that helps.

David

Edited by Guest
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Guest

I got some more data on this and realised how badly I'd processed it above (saturation hammer lol)

Notes below - I'm sure I still don't have this right!

David

 

Details

Object name

Andromeda Galaxy

Object ID

M31

Date(s)

11, 12 and 15 October 2017

Telescope

Altair 115mm

Camera

ASI1600MM

Luminance

89 x 1 min = 89 min

Red

16 x 2 min = 32 min

Green

24 x 2 min = 48 min

Blue

28 x 2 min = 56 min

Ha

0

Oiii

0

Sii

0

Total time

3.75 hrs

Frames

0

Processing

PixInsight / Bias, Flats, Darks / no noise reduction / no masked stretch (manual)

Notes

This is a reprocess of the image above

 I also made mistakes in the table regarding sub times – corrected here.

 Looking at my original process above its clear all I wanted to see was colour and so I hammered the saturation – something I don’t usually do – so for this version I avoided it and I think it looks a little better.

I have an hour of Ha data on this but having never combined it with RGB I’ll have to learn about all that now.

I think I really need to get more colour data on this too. Hopefully I will before M31 disappears into the West.

 

 I accidentally posted the wrong reprocessed image earlier - here's the one I meant to post

y4mtnQcA9fJGOvIyqFfTaMvJxyzU68wFuqZWxWD0

Edited by Guest

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Guest

I've integrated an hour of Ha data onto the Luminance sub - I've not done this before so not sure if I'm over cooking the stretch on the Ha / luminance sub

I used PixelMath to combine the Ha / Lum channels in their linear state, then stretched them, and then used PixelMath again to combine with the rgb

Does that sound right to PixInsight users?

Thanks

David

M31 HaLRGB

y4mYsxwKyAI-xYfyW1W1TeU4SPZXh7j-wxZduOqv

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Guest

I forgot to use SNCR (PixInsight) in the image above

Instead of applying it to the whole image (made it a weird shade) I applied a mask, set Protection Method to Additive Mask, the amount to .5 and unticked "Preserve Lightness" (if I didn't it wound up with a magenta haze across the core etc)

I'm not used to experimenting with Pixinsight - that was fun ! LOL!

y4m61pLGhSEnsSGNsJ12EK1nPrXFlGTwKp6w1wxJ

Edited by Guest
forgot to resize image before upload

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Guest

Further to my reprocess above I just realised that I hadn't applied a mask for LocalHistrogramTransformation and it's completely  trashed the background - little black dots everywhere - looks like i'll be reprocessing this one again 

David

 

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Guest

I think I'm finally happy with this - I just reprocessed it correcting the errors I made earlier - it's amazing how it takes hours each year to remember the nuances of processing, but once I got some practice I was able to totally reprocess this from scratch quite quickly.

I'm not sure if this just needs more data but at almost 5hrs its seems like it should have enough :-)

y4mA3yCrC0KYZtQjnSpEe-krA5bE9HqveEzglKPb

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Hi Dave. Looks like something went wrong in the background of this last effort. Huge magenta cast. I'm sorry i can't help with applying the ha as i use PS.

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8 hours ago, Allinthehead said:

Hi Dave. Looks like something went wrong in the background of this last effort. Huge magenta cast. I'm sorry i can't help with applying the ha as i use PS.

Thanks - yep you're right and I think it was the SCNR mask I used in the final step - might have had the mask inverted.

I've also noticed that, in trying to tame the "stick on patch" galaxy affect seen in the second to last attempt I probably under cooked the processing on the HaLum - I deliberately didn't push the brightness too much - looks like maybe not enough.

Also, I didn't use LocalHistrogramEqualisation to bring out the detail on the spiral arms, again to avoid the artificial look these galaxies can get when its not done properly.

Just looked at it in the cold light of day and it's amazing how you don't see these things when processing lol

I've attempted a few fixes seen below but I think I'll process it again - for practice - then I'm going to create a GIF of all the variants (don't think I can post those here) to see the morph from awful to today LOL.

Thanks again

David

y4mwQ3U6tKiT4azBioZU23TtHkTv3kCFfyF2jFfH

Edited by Guest

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Still like the first one best!  Looks spot on with great detail in the dust lanes

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Guest

I've had yet another attempt at this.

I've added the DBE, and tutorials from Harry's AstroShed (invaluable PI resource!)

What was really interesting is if you "blink" my most recent effort above, with the LRGB version here, you'll see I processed it, quite accidentally, almost exactly the same - but with DBE thrown in I've gotten rid of the gradient. I hadn't used DBE much as I could never get it to work right. My friend Nick encouraged me to revisit it and after watching Harry's AstroShed tutorial on the subject - I did it! :-) ....probably not perfectly but a good improvement I think.

I'm happy enough with the LRGB version to park that now, but I didn't get the Ha / red channel combination right and it looks  a bit murky :-)

Thank you to all who offered guidance, including my bud Nick!

David

LRGB

y4mMB_cgyPhodi3NOgE7Y_35IuB9RnvOK8EmCFLO

 

HaLRGB

y4mLjqD5sHcoMHEMviVYk-UD09HJGsHknIOEerfp

 

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