Cat's Eye Nebula with Billy Harris.

[ollypenrice]

A man after my own heart, Billy wanted to nail this one so we spent all week on it. Using the TEC140/Atik460 mono/Mesu 200 we captured the following, totalling about 21 hours:

RGB I hour per colour (6x10 minutes). Plus 11x30 seconds pre colour for the core.

Ha 8 hours (24x20 mins) plus 14x120 seconds for the core.

OIII 8 hours (24x20 mins) plus 12x200 seconds for the core.

Luminance 1.5 hours (6x15 minutes.)

The processing proved complex so I'll put some notes at the end of this post. Clicking on the image should take you to full size. The nice little galaxy is NGC6552.

 

Notes.

The core is incredibly bright and in short 'framing' subs just looked like a bright star. This initially had us wondering if the GoTo had failed!

We experimented with short sub exposure times because it was obvious that this would need high dynamic range layer masking. Our core subs worked quite well but could not 'fill' the over exposed core of the fully stretched long subs. If you decide to try this target it might be worth shooting a set of intermediate length subs as well. In this case I solved the problem by making a soft stretch of the long data and layer masking the shorts into that and then layer masking the result into the full stretch of the long data. This was done individually to the RGB, Ha and OIII layers.

The luminance was an afterthought to enhance that nice little galaxy. I haven't used it anywhere else but, starting from scratch, I would use it on the RGB as well.

The NB data was added to the colour channels in Photoshop's blend mode lighten. Ha to red, OIII to green and blue. The green-blue balance was done by placing the 'OIII to blue' image on top of the 'OIII to green' and adjusting the opacity to find the right (I hope!) teal blue colour.

In the 14 inch Meade SCT we could see no trace of the outer filaments but there was a soft glow around the bright central part.

Thanks to our robotic client Peter Woods* for the loan of his new generation Astronomik OIII filter. I liked it and will probably order one.

Olly and Billy.

*Just to be clear, Peter's rig is robotic but he is entirely human...

[Allinthehead]

Looks great 21 hours well spent.

[Star101]

That's a great shot Olly.

Very nicely done. I do like it.

And thanks for the detailed info on how you guys achieved the result. Much appreciated.

Dave.

[RichLD]

Lovely work Mr. Harris and Mr. Penrice!

Don't think I've ever seen a better rendition, congratulations! ?

[Pompey Monkey]

That's super, @ollypenrice and Billy!

There's super detail in the full size. What pixel scale are you imaging at?

I ask because I've been playing around with the drizzle integration in PI. These are crops from the same 21 subs, one drizzled, the other not. They've just been screen captured after an STF stretch.

I'm undersampling at about 2.6" PP, and I think it's worth the effort:

Edit: Nevermind, I worked it out at 1" PP. Drizzle might still help eek out that detail a bit though...

[ollypenrice]

10 minutes ago, Pompey Monkey said:

That's super, @ollypenrice and Billy!

There's super detail in the full size. What pixel scale are you imaging at?

I ask because I've been playing around with the drizzle integration in PI. These are crops from the same 21 subs, one drizzled, the other not. They've just been screen captured after an STF stretch.

I'm undersampling at about 2.6" PP, and I think it's worth the effort:

Edit: Nevermind, I worked it out at 1" PP. Drizzle might still help eek out that detail a bit though...

We're at 0.9"PP Paul. You're right, I should give Drizzle a whirl for the core details especially in Ha. Thanks,

Olly

[widotje]

Absolutely amazing, thanks for sharing and the detailed description.

[gorann]

Outstanding!

Zooming in I find planet Earth in the centre of the nebula!

[Horwig]

WOW

And I'm not usually lost for words.

 

Huw

[Horwig]

2 hours ago, Pompey Monkey said:

 

Now that is a good demo of Drizzle, must give it a go

 

Huw

[Rodd]

15 minutes ago, Horwig said:

Now that is a good demo of Drizzle, must give it a go

 

Huw

I actually don't see much of a difference.  I have never found drizzle to be "worth it"--except perhaps with no size increase just to round out the stars.  But even then---marginal.

[Rodd]

It looks like a splatter of paint, Olly.  A very clean, well formed splatter of paint.  It seems like a pretty tough target--well done as usual.

Rodd

[Shibby]

Awesome. Super clean and smooth. The result from your handling of the core is very pleasing.

[ollypenrice]

2 hours ago, Shibby said:

Awesome. Super clean and smooth. The result from your handling of the core is very pleasing.

Thanks. The core is always going to be slightly humiliating for amateurs, given Hubble's staggering rendition in which it is opened up to the minutest scrutiny. But it was nice to find key details, albeit on a tiny scale.

I haven't enjoyed a target so much for a while so I can heartily recommend it.

Olly

[billyharris72]

Just come across this - looking great Olly. I think the call re keeping the outer structure subtle was a good one.

For those giving me credit  - "with" pretty does mean I was there (though I did give the focuser an occasional tweak and nag about filters). The hard work and late nights were exclusively borne my my gracious host.

Cheers Olly - we both had a great time, and I learned an absolute tonne.

Billy.