Man v's M31 (3rd attempt)

[Iem1]

Afternoon guys,

I started a project on M31 last night, my 3rd attempt at it. It was my first ever attempt at a DSO, and shortly after I tried again, improved a little but neither were much good. Bad time of year, low in the sky and light summer nights. So I thought with my first 6 months in astrophotography almost done, and it being better conditions, I thought I would take another swing.

Not overly happy with results to be honest and wondering if it is worth adding more data tonight.

I only actually managed around 1 hour and 10 minutes of data (30 second subs with a WO Z73 on a SGP, iso 800, unguided, modded 600D) due to a slow start up, a meridian flip, and being extremely fussy about what data I kept. I must have deleted about 45 minutes worth of images due trailing, wobble, even the slightest of imperfections as i wanted to create a solid image. It was a bit windy and I am manually dithering between frames with only a 10 second pause between images, so I have to be quick or I can introduce wobble, will probably bump to 12-13 second delay between images to allow more time for the system to rest. It is a fairly short integration time, but does the data look ok to keep adding to? I feel it is still a little soft/slightly blurred. Doesn't seem sharp to me for some reason.

Full image with some processing;

 

Just the galaxy, having removed stars in StarX

 

 

I quite like the starless image, but I have not figured out a way to blend the stars back without introducing a grey cast to the image and blowing out the core too much, working on that!

Raw tif

result.tif

And here is my locked focus before starting (Stupidly forgot to take another at the end to see if the focus had shifted)

[Lee_P]

Looks great, especially for a short integration time. Keep going, add in as much good quality data as you can! It could probably handle being sharpened a little more during post-processing, if you're concerned about it looking a bit soft.

[vlaiv]

51 minutes ago, Iem1 said:

And here is my locked focus before starting (Stupidly forgot to take another at the end to see if the focus had shifted)

How can you tell if you have good focus there?

If I look at this part of image - that looks like serious asymmetry to me:

(look at three little balls of light right next to star - two on left are closer together than one on right).

[Iem1]

5 minutes ago, vlaiv said:

How can you tell if you have good focus there?

If I look at this part of image - that looks like serious asymmetry to me:

(look at three little balls of light right next to star - two on left are closer together than one on right).

I agree, but if i adjust to get those balls of light evenly spaced, I find the actual long lines themselves become unevenly spaced, this is something I have noticed for a while and I am unsure as to which i should be making evenly spaced, the balls of light or the long spikes/lines?

Looking at the original image above, I think the lines themselves are pretty evenly spaced, not perfect of course, but reasonable. Compared to noticeably unevenly spaced balls of light

[vlaiv]

4 minutes ago, Iem1 said:

I agree, but if i adjust to get those balls of light evenly spaced, I find the actual long lines themselves become unevenly spaced, this is something I have noticed for a while and I am unsure as to which i should be making evenly spaced, the balls of light or the long spikes/lines?

Looking at the original image above, I think the lines themselves are pretty evenly spaced, not perfect of course, but reasonable. Compared to noticeably unevenly spaced balls of light

I'm not very good at discerning focus with Bahtinov mask - that is why I never use one. I prefer FWHM and looking at the stars on screen (not sure how would that work with DSLR - if you can see stars on computer screen or you don't use computer at all).

Btw, data is good. SNR is good. I did quick processing and I did not need to use denoising at all. In fact, I was able to do some nice selective sharpening and still keep background smooth.

Only issue is with dark calibration (to be expected when camera is not cooled) - there is some unevenness in the background.

Here is the result of processing:

(for some reason I prefer this orientation on M31 - it took me a while to figure out which way it goes ).

[Iem1]

15 minutes ago, vlaiv said:

I'm not very good at discerning focus with Bahtinov mask - that is why I never use one. I prefer FWHM and looking at the stars on screen (not sure how would that work with DSLR - if you can see stars on computer screen or you don't use computer at all).

Btw, data is good. SNR is good. I did quick processing and I did not need to use denoising at all. In fact, I was able to do some nice selective sharpening and still keep background smooth.

Only issue is with dark calibration (to be expected when camera is not cooled) - there is some unevenness in the background.

Here is the result of processing:

(for some reason I prefer this orientation on M31 - it took me a while to figure out which way it goes ).

I am glad you noticed the difference in symmetry between the long spikes and the balls of light close to the star too, it has been giving me a headache for a while! Everything I read suggests that the long lines need to be evenly spaced (no mention of the balls of light), but I do wonder if I am doing something wrong or the B mask might be slightly damaged/bent or something. I use the B mask that came with scope (WO own for the Z73) but I will order a second generic mask and compare. if the weather holds tonight Il also try test both versions of focus and a single frame, evenly spaced spikes v's evenly spaced balls of light

That is a first for my data!  ..Usually it is emergency damage/noise control, I think the manual dithering is absouletly worth it now. Done it for both the Iris nebula and this attempt at M31, a lot of extra work for sure, but the results speak for themselves when compared to my older, non-dithered images. That and stringent screening of individual image quality. It hurts spending 4 hours out in freezing conditions, having to delete 30%-40% of data, to finish with 1 hour and 10 minutes of data, but it will be worth it in the end   

This was round 1, clearly before I knew back focus was even a thing! (first ever DS image!):

 

This was round 2, before I knew processing was a thing:

 

Current progress in round 3 with more data to come, with a very quick 10 minute process just to see what is there:

 

All the same equipment used, but with around 6 months worth of coaching and guidance from SGL folk in between 1st and last  

[ONIKKINEN]

1 hour ago, Iem1 said:

I quite like the starless image, but I have not figured out a way to blend the stars back without introducing a grey cast to the image and blowing out the core too much, working on that!

Did you follow the StarXterminator page instructions to create the starless-just stars-original layers? Goes like this:

If you want to create a layer with just the stars so they can be processed separately and added back in later, do the following:

• Duplicate the target layer twice
• Process the top-most layer with StarXTerminator
• Duplicate this layer, then make it invisible
• Select the first starless layer and set its blending mode to "Subtract"
• Merge this layer with the one below – this is now the layer with just the stars
• Move this layer to the top and set its blending mode to "Linear Dodge (add)"
• Make the remaining starless layer visible again
• You should now have three layers: the original photograph, the starless photograph, and the stars themselves

After this, hide the background layer (not needed anymore, but keep it for now to compare), set the blending mode of the starless layer to be "screen" (starless layer is the topmost layer if you followed the instructions). Then unhide both the starless and stars layer to have both visible at the same time. It should look the same as the background layer as it is created from that.

The just stars- layer does not have any background at all, it is set to 0 by StarXterminator. The only signal there is the stars and possible bloat around the stars if any remained after running the filter. You must use the starless layer to set the background to the level you like. I personally dont think the background should be 0, or even that close to 0 but it depends on the target. Galaxies have no defined "edge" in reality so a grey-ish background will look nice as the galaxy edges just sort of blend to the background. Play around with the black end of the levels to set it where you want, but i think values between 20-30 are typically the nicest.

A bahtinov mask is better than nothing to find focus IMO but its not the optimal way. Looking at HFR values on a computer/mobile device is a much better way to reach critical focus. Since you run unguided i don't think that's possible for you right now? But it might actually be better to eyeball focus with the camera screen on whatever is the max zoom mode on a barely noticeable star than do a bahtinov mask focus, although when i did DSLR shooting i found it way too fiddly and just accepted whatever focus the bahtinov mask reached.

[Sunshine]

Don't be displeased with your result, I think its great, your header "Man vs M31" is brilliant, has me chuckling a good bit. 

[Tim]

Not a bad attempt really, the stars are a little soft but that won't be helped by the slight off focus issue. When I look at the image you posted I wouldn't say that the large spikes are perfectly spaced, and as mentioned above, it is easier to see that at the base of the spikes.

I never normally like the starless images, but the galaxy really stands out in yours and it does it justice.

If it is any consolation, M31 is one of the trickier targets to get "right," the huge dynamic range between the core and the outer edges make it tricky, but you've got a nice balance here already. More data will give you better contrast in the dust lanes, more definition in the highlights like NGC206, and better colour depth and smoothness, especially in the few areas that show a bit of hydrogen emission nebulae.

Good stuff, keep 'em coming

Tim

[Clarkey]

5 hours ago, Tim said:

M31 is one of the trickier targets to get "right,"

Agreed. Easy to image but difficult to image well. A bit like M42. These two are nearly always the 'beginner' targets even though they are not easy to get a great result from. The best thing about both is that they can give pleasing results with minimal integration time.

FWIW I recently posted an M31 on the 'Deep Sky' imaging forum which was about 7 hours data. You wouldn't know it looking at yours. Keep going with more integration. You are definitely on the right track.

[Iem1]

Thank you for all the comments and advice guys, managed to push integration time to 2 hrs 51 mins, quite happy with the result! Working on process but I will finish in the morning (Working on blending, taking @ONIKKINEN's advice)

New starless of the 2hr 51 min data for comparison to earlier, I see a lot more sharper detail for sure

 

1 hour 10 min starless;

 

Edited November 29, 2021 by Iem1

[Sunshine]

I really like these starless images of M31, we are so accustomed to seeing past an infinity of stars towards the main target that sometimes the stars rob from the target itself. Seeing M31 this way all to itself really adds to its grandeur, in my opinion.

Edited November 29, 2021 by Sunshine

[vlaiv]

I think it is kind of funny calling "starless" image of something consisting out of stars

 

[markse68]

This seems incredible to me Lem1- good stuff! I’ve been trying recently from my bortle 8/9 skies with a much larger aperture and you are getting better detail than I am. Where are you imaging from?

Mark

[MartinT]

really nice shot, and so good to hear about the efforts and thinking that went into it.

[Iem1]

This is my attempt at it having recombined stars/starless;

Not particularly happy with it to be honest. The 'Starless' image (I do agree and see the irony, Vlaiv :D) or just galaxy image looks nice, the 'Stars' image without the galaxy looks nice...But add them together and the whole thing falls apart! Noise and speckles of feint stars (That seemingly do not appear in either image separately) pop up and detract from the image quite a bit I think.

The imaging was done very close to Elan valley, Wales. It is a Bortle 2-3 (Elan is 3, but where I go, 20 minutes further in is 2 apparently). M31 is perfectly placed up near the zenith, meridian flip both nights, and my imaging is done before the ~40% moon rises at about 23:30 too, which I think is important.

Edit: I should mention I do not use any light pollution filters, especially as I have access to some of the Darkest Skies in the UK with a 25 minute drive  Amazed my cheap USB Power bank and dew heater held its own over the last few outings. Lows of -2 degrees, puddles frozen solid under foot. That and my Duracell camera battery is a tank! manages 3-4 hours of life in those conditions, compared to my old Canon battery that came with the camera surviving maybe 40 minutes  

 

Forgot to post this last night, but here is the raw combined data from the two nights. Il add the original FITS file from Siril stacking + the converted TIF I take to PS, couldn't get Siril to play ball to my tastes or do Photometric Calibration so I did everything in PS   :

result.tif

result.fit

Edited November 29, 2021 by Iem1

[Iem1]

My secret weapon!

 

 

 

[Iem1]

Can not decide if I accidently ruined the image or made it better here..? Much less speckle and cast, but stars look..bleak?

 

 

[vlaiv]

1 hour ago, Iem1 said:

Can not decide if I accidently ruined the image or made it better here..? Much less speckle and cast, but stars look..bleak?

Background looks kind of blue and yes, stars are nowhere to be seen - except in galaxy of course

I personally find the image strange because of what I'm used to seeing in M31 images - there are certain stars / groupings of the stars that I expect to see - and some of them I use to judge quality of the image.

For example - great images of M31 start to resolve individual members of NGC206

Your initial image:

Last rendition:

Reference image found online:

Then there is "4 in a row" how I like to call that asterism:

Good M31 image will have those resolved and tight.

Here are they in luminance of M31 that I took some time ago:

But they are completely lacking in your last rendition.

[Iem1]

15 minutes ago, vlaiv said:

Background looks kind of blue and yes, stars are nowhere to be seen - except in galaxy of course

I personally find the image strange because of what I'm used to seeing in M31 images - there are certain stars / groupings of the stars that I expect to see - and some of them I use to judge quality of the image.

For example - great images of M31 start to resolve individual members of NGC206

Your initial image:

Last rendition:

Reference image found online:

Then there is "4 in a row" how I like to call that asterism:

Good M31 image will have those resolved and tight.

Here are they in luminance of M31 that I took some time ago:

But they are completely lacking in your last rendition.

Yeah its the result of a dodgy/accidental blend when I was playing with masks in PS while trying to clean everything up - to your eyes, that know what they are looking, it is very much ruined. To the lamens eyes, it's a pretty image 

I will try following ONI's steps again to see if I can get the stars back in without introducing the speckle/casts. 

[reezeh]

On 28/11/2021 at 15:40, Iem1 said:

This was round 2, before I knew processing was a thing:

 

You know;  I actually like this rendition and attempt. Do you know why? 

It's because this is how M31 looks through the telescope  (if you're lucky enough to be at a dark sky site and you have a good wide field telescope and eyepiece combination.

So,  I wouldn't chuck it because it's refreshing to see images that also reflect what you might see