Bortal 8 - M31 - help!!

[astrobena]

Hey everyone,

I was out recently in what felt like the first clear sky in years and got ~109 min of data on M31, minus 76 frames due to a 12mph wind, which left me with 69 min of data (each shot is 45 sec with ISO 200 tracked with skywatcher star adventurer). As mentioned in the title I captured all these images in a bortal 8 location, used an unmodified canon eos 400d and the skywatcher 75ed as the scope (with a flattener). I've attached my edit (warning: it is not great at all + slightly overedited to see what details are even there), and to be my surprise it looked very similar to an image of M31 with only 20 min of data which i captured a month earlier (both of which i used DSS and photoshop for). Now this may well have something to do with the way i edited it in photoshop or a different setting in DSS or just the fact that 49 more data doesnt make much of a difference considering im in a bortal 8 location, maybe you guys could help on that. I've attached the link to the original files (in the folder called 18.2.2021) as well as the stacked image from DSS (https://drive.google.com/drive/folders/12NT4TmLCXvTfOXNPE_l8UWPRpgO2VjLe?usp=sharing). I didnt capture any flat images but have dark and bias frames, all in their correpsonding folders in the attached link. It would be greatly appreciated if you guys could see if there is more data in this then i have managed to 'extract' using photoshop. (If you use different software and try and edit these files please tell me what you used) If there isn't then maybe do you guys have any images of M31 (or similar) from very light polluted skies that you could share here? (If so i would if you could share the full exposure time and gear that would be great)

 

Many Thanks!
 

Edited February 20, 2021 by astrobena

[Lee_P]

Hi from a fellow Bortle 8 imager! I’m learning PixInsight, so used that to have a crack at your data. I teased out more detail in the spiral arms, but there’s a lot of noise. I could have smoothed that out a bit, but left it in as it might help you to see it.

Basically, you need to improve the signal to noise ratio by taking many more lights, and maybe using a light-pollution filter as well. Adding in flats would help with the editing too.

A more experienced imager would be able to do more with your current data, but I think the key message – more data needed – would still stand 😊

-Lee

 

[astrobena]

2 minutes ago, Lee_P said:

Hi from a fellow Bortle 8 imager! I’m learning PixInsight, so used that to have a crack at your data. I teased out more detail in the spiral arms, but there’s a lot of noise. I could have smoothed that out a bit, but left it in as it might help you to see it.

Basically, you need to improve the signal to noise ratio by taking many more lights, and maybe using a light-pollution filter as well. Adding in flats would help with the editing too.

A more experienced imager would be able to do more with your current data, but I think the key message – more data needed – would still stand 😊

-Lee

Thanks alot, thats very helpful. If I take more pictures do they have to have the same exposure length. If not, and i take pictures with an exp. of 1min (15sec longer than the current ones) i would need new dark images? Im assuming I need new flats anyway due to dust stops moving around when transporting and for the bias I can just use the same ones right? (although making more doesnt take long at all).

[bottletopburly]

More data definetley try for at least 4 hrs of data ,Dither between frames to eliminate walking noise if you can  and most important take flat frames ,a lp filter may be helpful too .

Edited February 20, 2021 by bottletopburly

[bottletopburly]

You can make a bias and dark library take about thirty of each and change every quarter so don’t use one taken in summer and use in winter so the ambient temp is roughly the same , so on your imaging night all you need is lights and flats , take say 120 sec subs if you can depending on your setup not sure if you can dither with a star adventurer I think you can .

[Lee_P]

Dithering is a good shout, if you're able to. Ideally all your exposure lengths should be the same, so maybe you want to start again with longer lights. The exposure time for your darks should match your lights. If you take a good set of flat frames then they should be good to calibrate lights taken over imaging sessions spanning multiple nights, especially if you can keep your camera attached to the telescope (i.e. not shifting the dust around, or changing the camera's orientation).

[astrobena]

Hey, so i've been capturing some more data... around 3.5h now, again ive tried editing it and still not great results... This may well have something to do with my way of editing (i dont have an incredible amount of experience) and I will definitly have a look at some more tutorials but before i waste my time trying to achieve something that isnt possible, but is there anything you or anyone can do with this data, better then the first? (its in the same link: https://drive.google.com/drive/folders/12NT4TmLCXvTfOXNPE_l8UWPRpgO2VjLe?usp=sharing, this time the Autosave015.tif)

I would really appreciate any attempts at this!

[Lee_P]

10 hours ago, astrobena said:

Hey, so i've been capturing some more data... around 3.5h now, again ive tried editing it and still not great results... This may well have something to do with my way of editing (i dont have an incredible amount of experience) and I will definitly have a look at some more tutorials but before i waste my time trying to achieve something that isnt possible, but is there anything you or anyone can do with this data, better then the first? (its in the same link: https://drive.google.com/drive/folders/12NT4TmLCXvTfOXNPE_l8UWPRpgO2VjLe?usp=sharing, this time the Autosave015.tif)

I would really appreciate any attempts at this!

I'll have another crack at it. I'd like to do the stacking as well though, from the original light frames. Could you upload all of those, as you did with your first attempt?

[astrobena]

2 hours ago, Lee_P said:

I'll have another crack at it. I'd like to do the stacking as well though, from the original light frames. Could you upload all of those, as you did with your first attempt?

Brilliant, thanks! I've uploaded all of the files now and put them in a folder called 'Attempt 2' (still the same link)...

Now the imaging sequence of the 25.02 was with 50sec and ISO 100

The imaging sequence of the 26.02 was with 50sec but ISO 200 (I was planning on using this for all the following sequences) <-- here i accidently made an extra set of Darks with ISO 100 before i noticed it had the wrong ISO value and then made some more

And for the 27.02 its also 50 sec but for the ISO i wanted to use ISO 200 again (as mentioned) but for some reason forgot to do that and ended up with ISO 100, whereas the light, dark & bias frames are all ISO 200... (maybe here you could use the extra set of Darks with ISO 100 from the night before)

Oh and befor i forget: you will see there's a folder with all the images i've marked as not usable... I've done my best trying to sort them out, but im sure i have missed a few which actually could have been used / cant be used (in DSS I choose to stack only the best 95% for that exact reason)

I know this is by no means perfect in any way, but really just at the beginning of a steap learning curve with Astrophotography. Thanks again for helping me here.

Edited March 14, 2021 by astrobena

[Lee_P]

19 minutes ago, astrobena said:

Brilliant, thanks! I've uploaded (EDIT: I'm still uploading) all of the files now and put them in a folder called 'Attempt 2' (still the same link)...

Now the imaging sequence of the 25.02 was with 50sec and ISO 100

The imaging sequence of the 26.02 was with 50sec but ISO 200 (I was planning on using this for all the following sequences) <-- here i accidently made an extra set of Darks with ISO 100 before i noticed it had the wrong ISO value and then made some more

And for the 27.02 its also 50 sec but for the ISO i wanted to use ISO 200 again (as mentioned) but for some reason forgot to do that and ended up with ISO 100, whereas the light, dark & bias frames are all ISO 200... (maybe here you could use the extra set of Darks with ISO 100 from the night before)

Oh and befor i forget: you will see there's a folder with all the images i've marked as not usable... I've done my best trying to sort them out, but im sure i have missed a few which actually could have been used / cant be used (in DSS I choose to stack only the best 95% for that exact reason)

I know this is by no means perfect in any way, but really just at the beginning of a steap learning curve with Astrophotography. Thanks again for helping me here.

Okey dokey, just let me know when they're all uploaded

 

[astrobena]

7 minutes ago, Lee_P said:

Okey dokey, just let me know when they're all uploaded

 

All done now!

[Lee_P]

I started processing your data, but early on ascertained what the issue is.

I took all your Light frames and ran them through PixInsight’s SubFrameSelector tool. This is a way of measuring the quality of Lights. Each Light was given a FWHM measurement: the lower the number, the better quality of the Light. That flagged up the problem. Your 18 Feb data is very good quality, but most of what you obtained on the other nights is much lower in quality, and would likely only serve to degrade your final stacked image. I think this screenshot shows what I’m talking about quite clearly:

 

 

Your 18 Feb Lights are excellent, so your kit and skills are capable of it. I think you had low-level cloud on the other nights, which would explain the readings.

So, the reason I didn’t continue editing your data is that my next step would have been to axe any Lights that didn’t make the grade, which would be almost everything taken after 18 Feb. Meaning I’d have been left editing the original data! I hope that makes sense and is helpful. Aim for four or more hours of data as good as your 18 Feb efforts and you’ll be able to produce a stunning image

As an additional note for the future, I recommend trying to organise your data in a simpler way. My preference would be to have one folder containing all the Lights (all with the same ISO and exposure length); one set of Bias frames; one set of Dark frames; one set of Flat frames. I appreciate that this works well for me because I’m using a cooled astrocam, which makes using matching calibration frames easier.

Let me know if I can help further or if you'd like me to elaborate on any of the points

-Lee

[astrobena]

Yes that would explain that, thanks alot again... M31 was actually much lower over the horizon on the 25-27th then on the 18th plus i had a full moon on those three days which was not the case on the 18. But that really cleares things up for me, thanks alot again.