Updated 2023! Easy Comet Stacking in PixInsight.

In this video I will show you how to comet align and stack as well as create a final comet image using OSC data. This is an updated tutorial for 2023 and makes use of some new tools for PixInsight. Thanks to Katie Hughes for letting me use her comet data for this tutorial!
RC-Astro tools:
BlurXterminator: bit.ly/3FXxCtz
NoiseXterminator: bit.ly/3IudEIs
StarXterminator: bit.ly/3Cg4YBz
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Thanks for watching! Clear skies!

[@VisibledarkAstro]

Did you find this video helpful? Feel free to show your appreciation with a tip! paypal.me/visibledark

[@AstroHunter5280]

Hi, again! Have there been any new tools or processing changes since you made this video last? We have some pretty cool comets coming up this year...see what I did there...and I really want to get some comets captured in 2024. If there are, would you be able to make an updated version? Love your videos and thanks for speaking to us in a language we can all understand! You rock!

[@RQKimball1745]

This is pretty much what I've been doing. Nicely explained. One problem I have is using this technique with a galaxy in the image.

[@afryhover]

Thanks for this. We all have "comet mania" right now! 😂😂

[@anata5127]

This happens all the time once in 1-2 years, when bright comet is up there. People don’t want to take pictures of weak comets, which are plentiful up there.

[@FromGregg]

Thanks Shawn! Works great!

[@N4GW]

Excellent. Thanks

[@michael1026h1]

Perfect timing! Thanks!

[@sperdue1981]

Thank you so much for this!

[@denbergeron]

Great video Shawn. Thank you

[@astrocatinfo]

Many thanks for this great video !

[@jensunger6560]

fantastic video and right on time!

[@Astrolips2000]

great video! Thank you!

[@josephfoster6110]

Thank you! awesome

[@dswtan]

Nice and clear with the up to date PI steps, super handy - thanks Shawn!

[@user-bz2ns9em4u]

Excellent tutorial, thank you

[@cedrickizard4805]

such a great video thanks a lot for your work!

[@jeddymo7052]

Followed your process totally and was able to get a great final image of Comet Pons-Brooks. Total process took more than a day but was worth it. The Star Xterminator step on the the comet-aligned images (20 count) took 3-4 hours. Thanks!!

[@mathiasboehme]

Very straight foward. Great work - thank you 👍👍

[@Valencia1111]

Nice work Shawn. Will give it a go when we can image the comet from Sydney.

[@r.g.wilson4567]

Thank you Shawn for another great tutorial. I've been hoping you would cover the Comet update in PI.

[@dr.tobiaswagner9372]

Vielen Dank, das Video hat mir sehr geholfen 😊

[@allenbaylus3378]

very similar to the one from last year - I have been taking notes and really appreciate the effort to do this while we all have a comet to view.

[@damur21]

thank you so much

[@brianerneststephens]

Thanks for an excellent tutorial, looking forward to using it when the comet appears 'down under'

[@gregerianne3880]

Thanks so much for this video, Shawn! I was able to watch-pause-watch-pause a number of times and actually got a decent image using PI. Lots of work, these comets. 😄 Thank you for taking so much time making things easier (and possible!) for those of us without a lot of PI experience. It was very much appreciated!

[@StefanoZamblera]

Thank U very very much! Perfect timing 👏👏👏 best greetings and clear skies from sunny Italy 🌞

[@VisibledarkAstro]

Same to you!

[@zhouzun]

SXT is really helpful!

[@dmintz88]

Great video, Shawn. Thanks for doing this!

[@VisibledarkAstro]

My pleasure!

[@chasingghostsphotography4091]

Super helpful tutorial! Thanks so much.

[@VisibledarkAstro]

You're very welcome!

[@jackbernstein3029]

I have been struggling to pull my comet out. You have done several things that I haven’t. Time to play tomorrow and see if I am finally done! Thanks so much.

[@robb7342]

Another nice approach that is easy to follow Shawn - THANKS!

[@VisibledarkAstro]

You're welcome!

[@VincentProuvoyeur]

Thanks Shawn ! I did a great comet because of your method !

[@VisibledarkAstro]

Excellent!

[@wildlifephotographybeneath3609]

very well done and because of your great video and the deatiled instructions, I was able to work on my comet photos and get a reasonable result. thank you a lot!

[@VisibledarkAstro]

Awesome! Thanks for the comment.

[@shraddhapai]

Thank you, just took images of C/2022 E3 and Mars last night; looking forward to using your very useful tutorial to process these. Suggestion: A flowchart depiction of the workflow would be useful to give users a birdseye-view of the steps, given its complexity. People could just screenshot the flowchart for reference. Thanks again, appreciate you taking the time to teach us this.

[@greglight5808]

Turned out way better than mine. Lol dang nice image!

[@robertbowers6788]

Thank you very much for this excellent tutorial Shawn, it's the best I've viewed and I've viewed a lot. More Importantly thanks so much for the prompt help and answer to my question with an attached solution I am very grateful. I will be using and following more of your videos in the future as your style and clarity makes an old git like me more able to get my brain around things.

[@VisibledarkAstro]

You're very welcome!

[@nikivan]

It is preferable to do the comet alignment using the unregistered images (to avoid double interpolation). In this case, you'd need to set the Reference Frame to the same reference image used for star alignment.

[@cooky1875]

Tried to stack stars and comet in DSS last night and got black and white output. Going to try this method later 🤞

[@GeorgeSpacesOut]

I shot the comet in mono so after WBPP it looks like I may have to do this for each channel. Thank you for the video!

[@federicovelardo553]

Hi thanks for your video! Have you the mono LRGB flowchart? Thanks a lot

[@Aerostar509]

I thought you might use SCNR (Green) to remove the comet smear in the stars image and uncheck the Preserve lightness box along with a GAME mask over it, but it did add to the final green coma.

[@stxe34]

please create a video for mono cameras

[@VisibledarkAstro]

I actually just was able to acquire some data using mono setup the other night. It had been cloudy here for 3 months and I was relying on other peoples data as such. Most were shooting OSC. I'll put this on my list though.

[@stxe34]

@@VisibledarkAstro that would be great.

[@markhelton8032]

First of all, thank you very much for making a video to show this process that is both very understandable, and pretty easy to follow!! So I might have to go back and watch your WBP video as I just ran it, and it did not create a master light! Dark, Flat, and Bias master but no light master. What might I have done wrong? Thanks again, and keep making these videos!

[@VisibledarkAstro]

Not sure off hand why a master light wasn't generated. Do you have the WBPP log? It should show in there what went wrong.

[@markhelton8032]

@@VisibledarkAstro I will check. I am having some big issues with PIX anyway, this might be just the tip of the iceberg. SPCC just disappeared, even after doing an update. Also Generalize Hyperbolic Stretch. Someone told me that this might be an issue with the MAC OS. I have an email to PIX but have not heard back on what might be going on. StarX is also crashing PIX. It's an amazing program when it works! Thanks for your response

[@bengterlandsson7921]

Great tutorial Shawn. What processor, amount of ram and graphics card are you rocking? I feel a need to update mine.

[@VisibledarkAstro]

Sorry for the late reply! I am swamped with emails and comments from all the videos. I'm not running anything really fancy. I have a Ryzen 7 2700X, 64gb ram and an old NVIDIA GeForce GTX 1660 Ti. Nothing rockin really by today's standards I think. lol.

[@enriquebechet1]

Awesome . I was finally able to get a final image on this comet. I just have a question. Comet alignment from debayered images or registered (star aligned).

[@VisibledarkAstro]

Comet alignment is best done with the registered images (that have already been calibrated/debayered). That way the stars are fixed and the comet alignment tool can more effectively track the comet during its process.

[@enriquebechet1]

Took time to test , both ways came about identical result lol

[@gomanastro]

Nice job. Might have been nice to darken the background of comet only image, before adding stars ?

[@VisibledarkAstro]

Thanks. Darken or not to darken. It's all artist prerogative. I wasn't being to picky though as the main focus was to demonstrate the how-to of it all.

[@UrbanAstronomer]

That goddamn moon right now...

[@garyw.2224]

Great stuff Shawn, thanks for sharing your insights! One question...after the DBE on the comet image, around 13:38 in the video, the image background has a lot of streaky noise/artifacts in it. I'm assuming this is "debris" from the star extractions and the comet moving against the star field. I saw this in my first attempts as well. However, at around 13:42, when you grab and move the comet image to the right, the background is much smoother. Is there an extra step in there that I missed?

[@dazastronomy]

I've been having the same issue. Did starxterminator not solve that problem? I was hoping that it would, because winsorized and sigma rejection weren't working for me and I kept getting similar streaks.

[@garyw.2224]

@@dazastronomy No, it didn't for me, and you can see it in the starless comet image's background from about 13:10 in Shawn's video. Look at it on a big monitor if you can. I ran StarXT with AI 11 lite, I'm re-running it now with the full AI 11 to see if that helps.

[@dazastronomy]

@@garyw.2224 FYI, full AI 11 worked so much better for me than winsorized or sigma rejection. Took 12 hours overnight for remove the stars from 46 2-min subs. Still had some very faint streaks but it was a huge improvement. Hope it worked out well for you, too

[@garyw.2224]

Thanks Daz and MBR. Glad to know I'm not the only one. I came up with a couple of workarounds, that would probably send every PixInsight purist running away screaming :-) , but I wound up with a decent image.

[@dazastronomy]

@@garyw.2224 Awesome! Decent result is all that matters!

[@larrynall3993]

Very helpful. I was with you up until combining the two files in Pixelmath. My video resolution was too poor to make out the formula used. Can you help with that?

[@VisibledarkAstro]

You mean the pixelmath to combine unscreen stars? Its ~((~ImageA) * (~stars)) ...change ImageA to the name of your starless comet image.

[@larrynall3993]

@@VisibledarkAstro Worked! Thanks

[@falkinable]

@@VisibledarkAstro these are being multiplied??

[@webbles]

@9:55 when you state the pixel rejection is done in WBPP, does that mean that pixel rejection was done to each registered image? I was under the impression that pixel rejection would just happen on the master file that WBPP produces. Also thank you posting these tutorials, I used your previous comet stacking tutorial to produce my first comet image which I am very happy with!

[@VisibledarkAstro]

Yes that's correct it does apply the pixel rejection to the master file. I was thinking of the master light WBPP created. Now that being said, I tried both ways, with and without pixel rejection and didn't see a difference. Nothing that noticeable anyhow. So you can use or not, IMO. Whichever works best for your data. The older comet stacking video is still good and relevant. It just doesn't show some of the new methods we can do now. But following it will still provide good results. Glad it was helpful. Cheers.

[@briankotak403]

Hey Shawn. If I have Starnet++ instead of StarXterminator how do I create the starless comet file, as Xterminator does a batch process on the output files from the PixInsight Comet Alignment tool, but Starnet++ only uses a single file. Do I need to somehow stack the output of the Comet Alignment procedure first, or am I not understanding something? Many thanks. Dr B from Manitoba, Canada 🇨🇦

[@jeffratino5456]

You can use Image Container. It's at the bottom of the Process Tab. There are some videos on how to use it. I will say that I tried both, Starnet did not do that good a job on my comet subs. And I had used it previously on all of my images.

[@vtambellini]

I do have a question with this process. For some reason, StarXTerminator is taking off a large chunk of green from the top edge of the comet in each of the post wbpp and comet aligned exposures. Is there a method to remedy this? It also sometimes takes a large chunk of green out of the middle. Normally this would be fine as I could reintegrate the missing green from the stars, but that’s not possible when I’m batch preprocessing

[@uforoom]

same thing happened to me, did you find a solution?

[@rtumkur]

Thank you very much Shawn for this. Used the previous version of this from last year for Leonard and nice to have this update now. But for me in the 16:35 mark when you get the Stars Only image from StarXterminator, for some reason my image gets rid of the stars and shows only image with no stars in it. I am baffled. I have written to Russ about it too and sent him the before and after images. Anyone else had this problem? This is the first time I am using the StarXterminator, but followed Shawn's instructions.

[@rtumkur]

Russ helped me out with this. It was a Pixinsight problem. Once I did Window -> Cascade Windows, the stars only window showed up. Thanks Russ.

[@VisibledarkAstro]

Haven't ran into this myself but Tumkur's comment may be helpful. Russ is also good about helping as best he can.

[@Moshmallow96]

I'm following this tutorial right now and mine did the same, I just closed the StarXterminator process, I unchecked "Generate star image" and "Unscreen stars" then checked them again, applied the process and then it gave me the stars only image :)

[@chrisdavis8663]

Thanks so much for this tutorial! One question... I feel like I'm missing a step. I'm shooting with a Canon M6 II. After I stack the images, I still have the very green cast I always get. After I stack the comet images I don't have a way to use SPCC to calibrate it out. Did I miss a step? Debayering? Thanks for all you do for the astro community!

[@VasilisVify]

Did you press the unlink channels button in the STF process before applying the screen stretch ?

[@VisibledarkAstro]

That green cast is normal. Especially for OSC. Mostly due to the RGGB bayer matrix. You can use an unlinked stretch and it will not be green then. Have you tried this?

[@aliciarossiter8066]

This was an excellent tutorial. I have tried this. The only issue is that the batch processing of StarXterminator takes FOREVER. I have an M1 Mac and it takes 2 full minutes per picture. The other issue I have found is to be able to get a decent stretch of the starless comet. I cannot not manage well the GHS process which apparently is the best one to stretch a comet without blowing out the core. Do you plan to do a tutorial of GHS in the near future? Thanks again, I have learned a lot in your channel (and yes....I am subscribed!)

[@Dan_P.]

I'm with you. StarXterminator simply takes too long. I have a core i7 computer and plenty of RAM, and it takes 3-4 minutes per image, and I have 43 images. I will not keep it past the free trial. Starnet works fine, but this needs a batch option.

[@VisibledarkAstro]

Thanks for subscribing! I have tried GHS but didn't find the results as good as my own methods I normally use. I might revisit GHS though and see where it's at now. I think it was just updated as well. Have you tried Bill Blanshan's GHS pixelmath stretch? He has icons you can download and bring into Pixinsight to do stretching with.

[@aliciarossiter8066]

@@VisibledarkAstro Yes, I have downloaded Bills's stretch Pixelmaths, they are all fantastic. I have noticed 2 very recent updates to GHS and I wander if these updates make it more user friendly?. By the way I have processed the comet ZTF on Feb 10 following your tutorial. The comet was in conjunction with Mars and Barnard 22. Amazing!. It is posted in my Astrobin gallery

[@HelberPontes]

Does this method work with reframing during the night?

[@VisibledarkAstro]

Yes it should if using the registered lights.

[@kostasrogue]

Hi. 3 minutes exposure and no trail on comet? how?

[@pierspalmer9245]

Nice video - thanks, but the StarXterminator element is taking 13 minutes per sub, and I've got 60 subs; is this right? My PC is a full on workstation designed for Autocad; an Intel Xeon E-2146G with 16GB ram.

[@VisibledarkAstro]

If you're video card is an Nvidia you could try installing the Cuda speed hack which will speed up StarXterminator and BlurXterminator/NoiseXterminator as well.

[@georgenixon]

where can i find the ht stretch unlinked: pixelmath?

[@VisibledarkAstro]

Lookup "Another Astro Channel", that's Bill Blanshan's channel and he has download links in the video for it.

[@conradsanders8475]

Where can I download Bill Blanshan’s stretch process ?

[@VisibledarkAstro]

You can find them here kzbin.info/www/bejne/m56ceoSwl9B1q7c

[@tonyhabost1494]

Why does her comet looks like a round circle while I had mine's around 100s exposure but still came out with trails.

[@UrbanAstronomer]

How would this process look like if i did use flat frames? I have 200 debayered images from the BPP now but i dont know how to apply the master flat to every single debayered sub

[@VisibledarkAstro]

BPP or WBPP? Either way you can add your flats into WBPP as example and let it do its thing. It will then produce a calibrated master light but also individual calibrated and registered files which you can use.

[@UrbanAstronomer]

@@VisibledarkAstro I did BPP and it outputted calibrated an registered files, but didn't use the flats at all. It did generate a master flat, which when put on top of the debayered files do cancel out the dust spots and stuff.

[@orionnebula3487]

Well so I have about 90 Light frames and the StarXTerminator took about 6,5 hours to make all my lights starless 😅 And I already got a pretty high end PC^^

[@falkinable]

There's a way to use the gpu for that if you haven't done it already.

[@orionnebula3487]

@@falkinable how? :D

[@VisibledarkAstro]

Email me [e-mail] and I can get you a link to the instructions for the Cuda hack which will speed it up.

[@John_Hudson_922]

where can i get the ht stretch unlinked script? i can't find it anywhere

[@VisibledarkAstro]

Easiest would be to email me. Shawn (at) visibledark.ca. I can send it to you then.

[@richardsprouse4748]

StarXTermanater process batch doesnt work for me. On a fairly fast computer it still takes thirteen minutes per one comet aligned light to remove stars. Dont have a clue what to do to speed this up.

[@VisibledarkAstro]

You may need to install the Cuda hack. If your video card is an Nvidia model that it works with. Will speed up the process considerably using the GPU.

[@dochawk7391]

I’m new to PixinSight and in need of Instructionals to learn how to use it with a Mac.Where do I go to start learning? Anyone know of how to direct me to this.

[@dochawk7391]

I have the software loaded on my Mac

[@VisibledarkAstro]

You'll need a tutorial that takes you through step by step. I have a 3 hour tutorial on PixInsight. It was made in late 2021. It covers all of the steps from start to finish and comes with data you can follow along then. I need to update it to include new tools like NoiseXterminator and BlurXterminator but the tutorial itself does demonstrate how to do such things manually and more. If you're interested send me an email at [e-mail] and I can get you set up.

[@AstroHunter5280]

Where do we get Bill's Histogram stretch?

[@VisibledarkAstro]

Hi. You can find them here. He has a download link in his video description. kzbin.info/www/bejne/m56ceoSwl9B1q7c

[@AstroHunter5280]

@@VisibledarkAstro thank you!

[@leemaisel9794]

Not working for me. My extracted comet image comes out completely green, I cannot use SPCC on it, as the astrometric information was lost in the process, also no stars obviously.

[@theastrocave]

Hi, when in comet alignment I notice that your images don’t open with a green cast but mine does once stretched. How can I open without having green cast?

[@VasilisVify]

Did you press the unlink channels button in the STF process before applying the screen stretch ?

[@Katieyhughes]

When you open the stf click the top left tab the one that looks like a link and that should fix it for you.

[@cbrown596]

Maybe I'm just stupid, but I find it incredibly difficult to follow when your PixInsight seems to be configured in a non-standard way. That, or mine is configured wrong. I'm especially hung up on how you managed to get your Dynamic Background Extraction to automatically have 83 samples displayed @12:53, as mine starts off greyed out and presumably wants me to click around the integration frame.

[@VisibledarkAstro]

It reads like you are very new to PixInsight. And that's OK. The video was made for those with some knowledge already of the software. To make it for a complete newbie would have turned it into a much longer video that few would sit through and require much more of my time producing it. You may benefit from my 1 on 1 tutoring service. As for my PixInsight layout being non standard, I think many arrange it to their liking. I may have slightly adjusted the top menu icons. More so on the right side. But not much really. In fact it's laid out for the most part as it was installed. Why it would be so drastically different from yours I don't know. But all the processes are still accessible via the top menu bar and that is the same for everyone. My DBE created the sample points automatically because I created an icon for the process I can more easily apply. But yes if you start DBE from a menu option you'll have to click on the image for the cross to appear and then click to generate sample points. 😉

[@bobdonahue8965]

Weird - I followed the steps and... my "starless" integrated comet images (and all of the frames) have stars... I don't know why StarXterminator didn't do anything at all. (doubly weird because my experience with Blur/NoiseXterminator has been nothing short of OMG-WOW).

[@canon1shot]

New to PI and my PixelMath does not have those characters in there. How do i find the correct code?

[@VisibledarkAstro]

Hey Butch - what characters are you referring to? Can you elaborate?

[@canon1shot]

@@VisibledarkAstro it was the formula to combine the two images in PixelMath, I was able to find it in another video. Thanks for the tutorial, it was really helpful !

[@anata5127]

Couple of questions. Star XT recommend un lick right button for linear pictures. Why do you keep it? Second question is that I have 300 LRGB files by 10 sec each; batch processing in Star XT will take 48 hours. Way around?

[@dazastronomy]

It was going to take 15 hours to remove the stars from my 46x120s images... Maybe we just need faster computers lol

[@anata5127]

@@dazastronomy It depends on file size. My computer removes stars within 6 min from 11Mpix frame created by asi294 camera. So, removal from 50 frames will take 5 hours. This is not top computer, but it is i7 processor.

[@dazastronomy]

@@anata5127 I hear ya. Starxterminator works fairly quickly on individual images but takes so long for batch processing. I wish the traditional method of using winsorized sigma clipping worked better but I still get bad star streaks in my images that show up after background extraction. Was hoping star removal before integration would help but it will take too long...

[@anata5127]

@@dazastronomy Unfortunately, there is no way around. Star XT has to be used. Other approaches gave crap results.

[@dazastronomy]

@@anata5127 Agreed :(

[@bradleykotch]

Forget the StarX batch processing, and just do each frame individually and save.

[@paulomarto]

OK I've ran the starxterminator and when comet stacked there are still star trails. Not sure what went wrong. Shall I run starxterminator again on the calibrated, registered, comet aligned and starless files and see if it gets rid of any stubborn stars?

[@paulomarto]

So I've run starxterminator again and its not worked still. But having processed the data regardless. I can see in the final image that where there are 2 or 3 small stars together in a row, very close together. They have not been removed by star exterminator and have trailed. Is there any way you know of to make starXterminator more sensitive to remove these kind of stars?

[@VisibledarkAstro]

You could try selecting a pixel rejection in the Image Integration tool. One that fits with the number of lights you have to work with.

[@dadwhitsett]

Just a heads up....RCStarX takes FOREVER. Also, used DSS for same images...disaster. PI much better!

[@VisibledarkAstro]

Do you have an Nvidia graphics card? You could install the Cuda hack and speed up STX and the others. Didn't take to long for me. My system isn't overly powerful really.

[@user-hz9yg9oy6pSabirbek]

не плаьтит ху....

[@lachezarkrastev7123]

There is a point in the astrophotography, which if you cross ... this is not a photography anymore.

[@VisibledarkAstro]

Interesting thought. At what point though?

[@lachezarkrastev7123]

@@VisibledarkAstro when you start making collages :)