Which software/technique for processing comets?

[Leo S]

Hi all,

It's been a long time since I tried stacking images. I did previously use DSS, but am wondering, since my old processing PC died recently (will be building a new PC imminently), what software would be best to try/install? DSS did have some handy comet stacking features, but perhaps others do too?

I've submitted for a license to trial PI, which sounds like it could be useful for removing gradients. Either that or GIMP. For stretching I used CS2 in the past and will probably install that again, unless there is a better option available?

I did manage to steal a few images of C/2022 E3 ZTF in between the clouds early this morning after Moon set with the 1DxII + 180/2, but I did struggle to get good focus, and not sure how good the data is that I got - I wonder is someone could have a look and see if it's good data/worth processing? I'm attempting to upload now, and will post a link when/if it's done.

Link: https://www.dropbox.com/s/vg6ikmfiqrdytas/E3raws.zip?dl=0 (187 mb .zip file)

Edited January 30, 2023 by Leo S
link

[Elp]

DSS is still useful. I've started to use Siril more as you can do more things with it including background extraction. And it's free.

Edited January 30, 2023 by Elp

[Leo S]

Thanks. Have downloaded Siril and will give it a try.

It's nice that it's free. I've already run into a problem with PI - it wants an internet connection for the trial, but my editing PC does not have one.

[Elp]

It probably has to download some files first, it'd be odd otherwise needing an internet connection to run.

Sirils developer has easy to follow tutorials on its website too. The software is laid out fairly well though for you to understand how it works without tuition.

[Leo S]

I'm just having a play with it for the first time, on my new build. Quite a learning curve, at least for someone who has not done much stacking in the past!

One thing I am stuck on is how to get to the "Photometric calibration" dialog - it's greyed out in the menu and I'm not sure why. I'm trying to follow the Sitil tutorial on comets here. I've followed it to the letter, but skipped the pre-processing step as I have no darks/bias/flats.

Any ideas?

 

[Elp]

7 hours ago, Leo S said:

Any ideas?

Is the data you're using a colour image? You'll know as it will show R/G/B/RGB tabs at the top left of the image.

[Leo S]

4 hours ago, Elp said:

Is the data you're using a colour image? You'll know as it will show R/G/B/RGB tabs at the top left of the image.

Yes.

I think I may have missed one thing out. Is the naming of the intermediate files crucial? I chose my own name!

Edited February 11, 2023 by Leo S
typo

[Elp]

No I don't think it is. PCC hardly works for me as it needs to be a linear unstretched uncropped image, when I do use it the star colours seem washed out so I just adjust colour curves manually later.

[Leo S]

23 minutes ago, Elp said:

No I don't think it is. PCC hardly works for me as it needs to be a linear unstretched uncropped image, when I do use it the star colours seem washed out so I just adjust colour curves manually later.

Thanks. I'll try skipping that step and see where it gets me.

[Varavall]

For processing comets I use ASTAP, Starnet++ and GIMP. ASTAP has a manual alignment mode specially for comets. Below is the result of last nights RGB imaging of C-2022 E3 (ZTF). If interested I can post the workflow. I still have a few artefacts from Starnet to clear up and the green tinges around the edges to make the image perfect!

Adrian

Edited February 11, 2023 by Varavall
Added comment

[happy-kat]

That's a super image.

I used ASTAP and had a great circular star trail image but I wanted to stack on the comet and the stars.

[Varavall]

1 hour ago, happy-kat said:

I wanted to stack on the comet and the stars.

Hi

Stack twice or maybe 5 times if you are using rgb filters. 

First stack on the stars in ASTAP, then put the stacked image through Starnet++.

Second, go to GIMP open the starless and starry images as layers, then with the starless image top make it "subtract". That gives you the star field without the comet which v=can be tweaked for the stars.

Third, run all the subs through Starnet++ (I create a batch file and use the CLI version) to leave just the comet.

Fourth, stack on the starless comet subs in ASTAP with the manual alignment process. If using RGB filters, then just stack the subs for each filter separately, and save that with a name so you know which colour filter.

Fifth, open as layers all the starless comet stacked images with the images in second step above.  Align the comet images, then create a new layer from visible for just the comet and tweak for personal preference, then move that layer above the star field layer and make it "screen", then make new layer from visible.

Sixth, tweak image until satisfaction is achieved.

Simples!

[happy-kat]

Thank you for sharing what you did.  

Looks like I'll have to starnet++ to my tool base

Though ASTAP is great I am not looking forward to comet registration on 300 lights.

[Varavall]

2 minutes ago, happy-kat said:

I am not looking forward to comet registration on 300 lights.

Depends if you have a CRAY. It took my laptop 3 hours to process just the 30 subs!

[Leo S]

5 hours ago, Varavall said:

For processing comets I use ASTAP, Starnet++ and GIMP. ASTAP has a manual alignment mode specially for comets. Below is the result of last nights RGB imaging of C-2022 E3 (ZTF). If interested I can post the workflow. I still have a few artefacts from Starnet to clear up and the green tinges around the edges to make the image perfect!

Adrian

Thank you for the kind offer. I might have to take you up on it at some point, if I can't get my head around Siril. Great image BTW. I wonder what caused the artifacts low down on the left of the image - very strange looking!

[Varavall]

12 minutes ago, Leo S said:

I wonder what caused the artifacts low down on the left of the image

It's something from Starnet++ I think. I am doing some more imaging of the comet tonight so I have something to compare and contrast.

13 minutes ago, Leo S said:

Great image BTW

Very kind of you ☺️

[Leo S]

2 hours ago, happy-kat said:

Thank you for sharing what you did.  

Looks like I'll have to starnet++ to my tool base

Though ASTAP is great I am not looking forward to comet registration on 300 lights.

Is your PC a bit long in the tooth? I think it took a few seconds to register 29 lights in Siril (using the "global" setting) on my new build (Ryzen 5 5600X - 6 cores). Mind you I'm not even sure I'm doing everything (or anything) right! Hopefully building a 12 core system next week which should be at least a bit faster!

[Leo S]

Should the window showing the image in Siril be saying B&W in the top left corner - perhaps that is the problem with the colour calibration? The original RAWs are colour, so not sure why this is, or how to avoid it?

Never the less, I tried to process a stack of 29x 5s exposures, and imported the result into CS2 to have a play with it there, but I was only able to import as .png after taking a "snapshot" with Siril - I couldn't see a way to save/export the result?!

Anyway, not sure how to remove the vignetting (no flats), and how/when to stretch, but here's what I have so far:

[Varavall]

20 minutes ago, Leo S said:

Is your PC a bit long in the tooth?

Yup, 10 years old. It's a dual quad core i7, but a few generations back. The lengthy processing time was Starnet++; 5 minutes per sub. I have time on my hands so I do other things whilst the laptop trundles along.

22 minutes ago, Leo S said:

Hopefully building a 12 core system next week

Slightly envious 😖

[Elp]

You'd be surprised how much difference a generational change in cpu makes, never mind a few years gap, though it's not financially practical (or ewaste sensible) to upgrade at such a frequency.

Edited February 11, 2023 by Elp

[Elp]

1 hour ago, Leo S said:

Should the window showing the image in Siril be saying B&W in the top left corner

It will treat the images you import to run as a sequence as mono as far as I'm aware (if you've just opened a single image it will be either b+w or R, G, B/RGB), you have the check box at sequence generation (first tab) or at pre processing (I think, not got it open in front of me) to enable debayering to make them process and save as colour (be sure to check the Bayer pattern in the settings are set correct to your camera sensor RGGB etc is usually the main pixel layout type). If they are from a colour camera at each step where there's a CFA option enable that too.

I think it treats it as mono initially as calibration frames are normally processed as such, I process all my master darks, dark flats and flats as b+w images and then debayer at the stage when the master dark and master calibrated flat are applied to the lights, they are then treated as colour from then on in the preview view.

To export an image there's a down arrow button on the top right row of buttons (it looks like a download icon), it will open a file browser dialog box and you input your filename and file extension and save, it will open another dialogue box for the file settings, you can keep them at default and save.

Edited February 11, 2023 by Elp

[Leo S]

13 minutes ago, Elp said:

You'd be surprised how much difference a generational change in cpu makes though it's not financially practical (or ewaste sensible) to upgrade at such a frequency, never mind a few years gap.

I try to get about 10 years out of my builds, but if they can go a bit longer I'm happy to let them. It's a big jump in performance just switching from Intel to AMD at the same price point it seems. First time using Ryzen processors for me in a build, and I'm impressed. Not really surprising when comparing benchmarks for my last processing PC vs the two new AMD builds I have on the go - each upgrade is about double the performance! 

AMD Ryzen 9 5900X @ 3.7GHz
Scores: 39,275

AMD Ryzen 5 5600X @ 3.7GHz
Scores: 21,943

Intel Core i7-6700 @ 3.40GHz     
Scores: 10,024

To be fair I was forced into building a new system for processing, since my old one died, but after I started to build (with the 5600X) I happened to come across a great deal for the 5900X. In fact I managed to find most parts on offer (PSU, case, GPU, and, all the SSDs), so it was hard to resist putting together a second new build, especially seeing as I'll likely soon be needing a replacement for this PC I'm typing on now, as it's around 10 years old, and not built with the best components (it's actually a pre-built PC I bought when the previous one died suddenly), so I will probably retire this one early to prevent what happened last time, even though that's not normally what I'd do, but I don't trust this as much as I do my own builds!

That, and I'm doing more and more editing of 4K footage, so I could use some power. The old system was really struggling, even with 4k 30 FPS, but I have also started collecting 4K 60 FPS footage, which I have not even tried to edit - it just would not have been possible with my old "power" PC.

The biggest nightmare has been finding GPUs at reasonable prices. I did manage to find a little of a half decent GPU, but still can't bring myself to pull the trigger on either RX 6600 8gb (more power than I need and more than I'd like to pay) or the older RX 6500 XT (not quite as much power as I'd like, and a big step down in memory interface, but closer to what I wouldn't mind paying). There does not appear to be anything in between those two worth looking at!

[Leo S]

1 hour ago, Elp said:

It will treat the images you import to run as a sequence as mono as far as I'm aware, you have the check box at sequence generation (first tab) or at pre processing (I think, not got it open in front of me) to enable debayering to make them process and save as colour (be sure to check the Bayer pattern in the settings are set correct to your camera sensor RGGB etc is usually the main pixel layout type). If they are from a colour camera at each step where there's a CFA option enable that too.

I think it treats it as mono initially as calibration frames are normally processed as such, I process all my master darks, dark flats and flats as b+w images and then debayer at the stage when the master dark and master calibrated flat are applied to the lights.

To export an image there's a down arrow button on the top right row of buttons (it looks like a download icon), it will open a file browser dialog box and you input your filename and file extension and save, it will open another dialogue box for the file settings, you can keep them at default and save.

Thanks for those tips. I'll go and have another play with the stacks. Hopefully I can at least get some of the colour to come out!

[Leo S]

5 hours ago, Varavall said:

Yup, 10 years old. It's a dual quad core i7, but a few generations back. The lengthy processing time was Starnet++; 5 minutes per sub. I have time on my hands so I do other things whilst the laptop trundles along.

Slightly envious 😖

Have you checked prices on the high core CPUs recently? While still not super cheap, they do seem to have come down a fair bit. I managed to get my 5900X for £310 (currently on Amazon for £317).

Edit to add: There are some useful tools that can help you find a bargain/avoid being ripped off, for example cpubenchmark.net:

The chart below shows how the price has varied for the AMD Ryzen 9 5900X

 

Edit #2: Here is another useful tool: https://uk.camelcamelcamel.com/product/B08164VTWH?context=search

 

I'm also slightly envious of those with 16 cores, and GPUs with triple fans!

Edited February 12, 2023 by Leo S

[Varavall]

6 hours ago, Leo S said:

Have you checked prices on the high core CPUs recently?

Yup, but the power consumption of the CPU alone is what I need for the entire system. I live off-grid so the compromise for having no energy bills is that I can only run some things when I can. So I need a mighty processor system that consumes no more than 150W max in total, preferably nearer 100W. Well I could spend 25k to beef up the solar arrays to allow the running of a high spec PC, but just think about the telescope, camera and mount 25k would buy.