Advice on capturing the comet.

[Rustang]

I have done some light online research in regards to technique used for capturing comets but I wanted to confirm how to go about it. Firstly I have a mono camera so it will have to be captured as LRGB, does the centre burn out quickly?, just trying to gauge exposure length. I'm guessing I have to locate it manually then start tracking? I normally use APP to get on target but I'm guessing I wont be able to do that because it wont be in APP's database? I believe I will have to track on the comet itself to get the correct speed/movement without star trails or is it possible to sort the stars out later? I think I've seen people do this is stacking, the stars separately then the comet etc, is that true or if my stars are trailed then they stay that way instead of fixed!? So if I use the comet to track on, I guess I select the comet as the star in PHD2? I normally track side rail at 0.5x, if I was to do that would it keep up with it?

Just trying to make things easier for when and if I give it ago as I've never captured a Comet before.

Edited January 26, 2023 by Rustang

[Yawning Angel]

I tracked the stars for my attempts, then created a master star image. My thinking is the mount want to track stars, where as the comet movement if going to need it to work harder...plus comets are fuzzy anyway 🙂

After that, you can do a comet stack, aligned on the comet and a strong rejection algorithm can reject the stars (experiment with rejection settings)

Good luck!

Edited January 26, 2023 by Yawning Angel

[Rustang]

6 minutes ago, Yawning Angel said:

I tracked the stars for my attempts, then created a master star image. My thinking is the mount want to track stars, where as the comet movement if going to need it to work harder...plus comets are fuzzy anyway 🙂

After that, you can do a comet stack, aligned on the comet and a strong rejection algorithm can reject the stars (experiment with rejection settings)

Good luck!

Ok cool so track as normal then as if it was a nebula. I think my main concern is locating it and pointing everything at it, I currently dont have a finder on my imaging rig and I dont really wont to take it all apart or add anything so trying to get the camera on target with no eyepiece or finder isant going to fun! 

Edited January 26, 2023 by Rustang

[Yawning Angel]

I used the Orbitals plug-in for NINA, but if you can use Stellarium / ACSOM to point, it can easily be added to it's database

[Rustang]

1 minute ago, Yawning Angel said:

I used the Orbitals plug-in for NINA, but if you can use Stellarium / ACSOM to point, it can easily be added to it's database

Oh cool, I didnt realise I could add it to a database, I have the ASCOM platform for my imaging gear but I use Astrophotography Tool so could I add it to that? I will go and research that in the meantime, it would make my life much easier if I do give it ago. 

[ONIKKINEN]

5 minutes ago, Rustang said:

Ok cool so track as normal then as if it was a nebula. I think my main concern is locating it and pointing everything at it, I currently dont have a finder on my imaging rig and I dont really wont to take it all apart or add anything so trying to get the camera on target with no eyepiece or finder isant going to fun! 

The coordinates that Stellarium reports the comet to be in are fairly accurate, within half a degree for sure at least on the 3 comets i have tried so far. You can manually slew to those coordinates and you will at least see it in the frame and can adjust manually from there.

[Rustang]

2 hours ago, ONIKKINEN said:

The coordinates that Stellarium reports the comet to be in are fairly accurate, within half a degree for sure at least on the 3 comets i have tried so far. You can manually slew to those coordinates and you will at least see it in the frame and can adjust manually from there.

Good point, I'm pretty sure I can enter the coordinates into APP somehow or the mounts ASCOM/EQMOD controller.

Edited January 26, 2023 by Rustang

[adyj1]

I had a quick look at it last night - used SkySafari on my phone to locate the comet and see the closest star, used Cartes du Ciel on the imaging PC to find the same star, and then used the CdC ASCOM telescope integration to tell EQMOD where to point. Then dropped into NINA to fine-tune the framing and take a few exposures.

I really must get the Orbital plugin sorted...  

[woldsman]

+1 to the NINA Orbitals plugin. Download it, update it with the latest comet data, select "comets" in the drop down menu, start typing "C/2022...." & it appears. Then just scroll to the "Frame" button, click it and the Mount slews to target. 

Imaged using a mono camera.  Went for 18 x 60" L and 6 x 60" for each of RGB. Next attempt may go for more subs at 30" for reasons explained below.

The really challenging bit is processing. Like many, I used the free Deep Sky Stacker for stacking. Produced two stacks for each filter: one stacked on stars and the other on the comet. The star stack is easy to handle: you can 

get a stars only background without difficulty. The comet stack is the problem and the issue is getting rid of the star trails and blending with the stars only image. With basic software (ie not Pixinsight or Photoshop) - not everyone has these)  I think the

way to address this is to take the subs for each filer in the time order they were captured and produce two comet stacks: one for odd numbered subs and one for even numbered subs. Then star removal (eg Starnet++) works better and you can 

blend the two-comet only stacks. This is a form of "sieving".  With 30" rather than 60" subs, there are obviously more subs in each pile so it should produce  better result with shorter trails as well. Would welcome comments on this approach. If the method is crass and better approaches exist,  am all ears! Am aiming for a practical approach that produces an acceptable result versus a prize-winning image  

 

Edited January 26, 2023 by woldsman

[jfrijhoff]

I hope to get a clear night to try and image the comet (first time ever for me). I was also planning on 30sec subs, and I just have the Samyang 135mm, so hopefully star trails in the comet-aligned image won't be too bad. I'll be using Siril to stack, and there seem to be directions on their website to do it (https://siril.org/tutorials/comet/), maybe it also helps in your setting.

[Rustang]

10 minutes ago, jfrijhoff said:

I hope to get a clear night to try and image the comet (first time ever for me). I was also planning on 30sec subs, and I just have the Samyang 135mm, so hopefully star trails in the comet-aligned image won't be too bad. I'll be using Siril to stack, and there seem to be directions on their website to do it (https://siril.org/tutorials/comet/), maybe it also helps in your setting.

The next few days are not looking great weather wise, hopefully I haven't missed my chance!

[Yawning Angel]

8 minutes ago, Rustang said:

The next few days are not looking great weather wise, hopefully I haven't missed my chance!

If you want to try out processing some data, let me know and I'll try to upload it somewhere 15 x 60 per channel

[Rustang]

1 minute ago, Yawning Angel said:

If you want to try out processing some data, let me know and I'll try to upload it somewhere 15 x 60 per channel

Yeah that would be great, thanks. Maybe a shared dropbox folder would be easier!?

[jfrijhoff]

11 minutes ago, Yawning Angel said:

If you want to try out processing some data, let me know and I'll try to upload it somewhere 15 x 60 per channel

Ditto!

[Yawning Angel]

Link to Google drive, Comet C/2022 E3 (now removed)

1.1GB zip:

15 x 60 sec L
15 x 60 sec R
15 x 60 sec G
15 x 60 sec B

Master Flats LRG & B
Master Dark, 60 sec

Tracked on the stars

My version is here: C-2022 E3 (ZTF), LRGB

I'll leave it up for a few days , and I'd love to see what you do with it 🙂

Edited January 31, 2023 by Yawning Angel

[Rustang]

5 hours ago, Yawning Angel said:

Link to Google drive, Comet C/2022 E3 

1.1GB zip:

15 x 60 sec L
15 x 60 sec R
15 x 60 sec G
15 x 60 sec B

Master Flats LRG & B
Master Dark, 60 sec

Tracked on the stars

My version is here: C-2022 E3 (ZTF), LRGB

I'll leave it up for a few days , and I'd love to see what you do with it 🙂

Thanks, im not sure il match your processing but will give it ago plus it will be good practice for if i can capture some data of my own 

[Yawning Angel]

10 minutes ago, Rustang said:

Thanks, im not sure il match your processing but will give it ago plus it will be good practice for if i can capture some data of my own 

We get limited time with these objects, so hopefully having something to practice on helps 🙂