M81 and M82 - 4h

[ONIKKINEN]

Somewhere around 240x60s exposures from a bortle 4 area in good seeing and transparency:

So far the sharpest data i have yet to capture, but unfortunately a bit affected by some optical gremlins if you look to the corners so room for improvement still. I dont think they detract from the 2 main subjects so not too worried about that.

Stacked in APP, Linear processed in PI with SPCC, BlurXT, NoiseXT, some HDRT. Nonlinear fiddling with Photoshop including StarXT. I added the stars within M81 back to the starless layer from the stars-only where layer (StarXT likes to deposit stars resolved within galaxies to the stars only layer) which is why M81 looks a bit sparkly. Not sure if i have overdone it, its still a new workflow for me so might have another opinion tomorrow or a week from now.

Background looks a bit funky because there is IFN pushing through at some points. Not enough to try and process them out as a part of the image but also enough that i dont want to try and bruteforce remove it. If i get 2 or 3 nights more under similar conditions it should be possible to tickle it out of the noise floor. I thought about not posting yet because i do want to see the IFN, but who knows how many months/years from now i get the opportunity to shoot under dark moonless conditions again so might as well post now, and the galaxies being so bright are at a point where i like them to be anyway.

[Astroscot2]

Thats a lovely sharp image , your images really show what a well collimated and mechanically sound Newtonian can do.

 

Impressive!

Mark

[ONIKKINEN]

9 minutes ago, Astroscot2 said:

Thats a lovely sharp image , your images really show what a well collimated and mechanically sound Newtonian can do.

 

Impressive!

Mark

Thank you very much! I have cropped a little bit off the edges where double diffraction spikes start to appear. Jury is still out on whether its backfocus, collimation, or tilt induced collimation relataed since it was the second time out with the scope after i swapped the aluminium tube to a carbon one, so the focuser could be a little skewed against the tube still. Sharpness in the middle was for around 2.2-2.5'' fwhm stars.

[Astroscot2]

Im in the progress of making modifications to my CT8, I knew I would need to when I bought it.  The original spider was twisted and the replacement not much better, will try it first before I look at replacing.  Im swapping out the focuser and adding longer top and bottom dovetails to reduce the flex with the thin Carbon tube.  Could I ask you method for squaring your focuser to the tube?

Thanks

Mark 

[ONIKKINEN]

1 hour ago, Astroscot2 said:

Im in the progress of making modifications to my CT8, I knew I would need to when I bought it.  The original spider was twisted and the replacement not much better, will try it first before I look at replacing.  Im swapping out the focuser and adding longer top and bottom dovetails to reduce the flex with the thin Carbon tube.  Could I ask you method for squaring your focuser to the tube?

Thanks

Mark 

I just eyeballed it, will try with spirit levels next. I will orient the tube so that its perfectly level and adjust the focuser until the spirit level agrees that both the focuser drawtube and tube are even. I have a Baader diamond steeltrack which is adjustable in both pitch and yaw so it shouldnt be too difficult.

By the way, try this spider if the replacement is also unworkable: https://www.teleskop-express.de/shop/product_info.php/info/p9317_TS-Optics-massive-Metal-Spider-for-8--Newtonian-Telescopes-D-223mm.html

I installed that on my VX8 and it is a lot better. It only barely fits inside the tube so it kept the tube from collapsing, unlike the thin and flimsy spider originally. Pretty sure the VX8 and CT8 share the same spider so might be a decent fix for yours too.

Edited December 28, 2022 by ONIKKINEN

[Astroscot2]

Ive been online looking for a replacement spider,  The CT8 has an inner tube dia of 255mm which is a bit larger than the VX8 tube, TS dont seem to have a spider that would be a good fit for this diameter tube.  I saw this option but its a but pricey ?  RB-Carbon Fiber Double Spider | RB-Focus (rbfocus.net)

 

Mark

Edited December 28, 2022 by Astroscot2

[ONIKKINEN]

1 hour ago, Astroscot2 said:

Ive been online looking for a replacement spider,  The CT8 has an inner tube dia of 255mm which is a bit larger than the VX8 tube, TS dont seem to have a spider that would be a good fit for this diameter tube.  I saw this option but its a but pricey ?  RB-Carbon Fiber Double Spider | RB-Focus (rbfocus.net)

 

Mark

Carbon fiber parts cost an arm and a leg so not that strange of a price. 0.5mm thickness is a little bit too risky imo even if its carbon fiber. Better than the stock one by a mile still i would imagine.

The metal spider i linked comes in a 286mm variant, you could shorten the vanes yourself to make it fit. They are held to the center simply with 3 screws so you could remove them, shorten each by 35mm and refit them.

[ONIKKINEN]

Took another go at processing this to try and bring out the IFN:

Looks dirty and noisy, but it is there. Still with the same 4h of data as have not had a chance to image since capture, surprised that there is so much in just 4h. Had to work for it though, as i used all the tricks i could think of: binning x4 as opposed to x2 of the original, processing only luminance from that to the point where the IFN is the least worst in terms of noise and stretch, resampled back to 200% or the original size in order to overlay that on a galaxy stretched image still at 1.51''/pixel. Some masking and eraser in Photoshop to selectively apply the luminance layer on just the IFN and the fainter parts of the image so that the galaxies dont saturate (would saturate with the IFN stretch). Stars added in last.

Judging from this result with just 4h it should become a very nice IFN image if i manage to add a couple of nights more, but weather will be deciding that in the end.

[jpoulette]

Wow - forget the "dirty & noisy", that's beautiful image.  Hopefully I'll be able to capture something half as interesting. Thanks for sharing. 😎