M27, RASA8/QHY268c/NBZ

[tomato]

Imaging a planetary nebula with an F2 RASA, perhaps not a good idea but this is the scope I have set up currently and I wanted to go deep to see if I could capture the 'Butterfly Effect' outer nebulosity. This is 115 x 3 mins with the RASA8/QHY268c/NBZ combination, all captured in Nautical darkness.

For sure, the object is a bit lost in the full FOV but imaging at 1.947 arcsec per pixel enables a substantial crop to be made. It has been discussed elsewhere on SGL that an 11" RASA might be a candidate for the elusive imaging scope all rounder, but I think there would still be some trade off on detail compared with the traditional longer FL refractor or reflector.

However, an IMX 571 camera coupled with a 14" RASA would be imaging at just under 1 arcsec per pixel, the trouble is I would need to liquidate my Esprit 150, RASA8 and a camera or two to afford one, but it is an interesting concept.  I understand this size aperture was specifically manufactured by Celestron for use by the amateur community to identify and track small items of orbiting debris (~1 metre in size). Does that mean every sub would be festooned with dozens of satellite trails?

Crop

[windjammer]

>> Does that mean every sub would be festooned with dozens of satellite trails?

Of course, that's our fate!

Pic full of possibilities - are you sure a reprocess aimed at the planetary would not improve it ?  Or is it baked in ?

Simon

[tomato]

Thanks, I’m afraid this is currently my best endeavours on processing the PN. First, significant LP was first removed with APP’s tool then BXT and SXT applied in PI followed by a masked stretch. More processing in AP  on both the stars only and starless images, then recombined with PixelMath and a mild application of NXT.

[tomato]

Well, thanks to @windjammer's encouragement, I have had a go with masked layers in AP, so now less of an overblown core.

[Tomatobro]

wow I see what you mean. It looks as if the faint lobes are being ejected from the central bar structure.

[symmetal]

Yes, your second processing shows M27 a lot better.

It looks like SXT had a hard job trying to construct the background and created the mottled look. This RGB image shows how little background there is visible for SXT to work with. A second processing with less background stretch combined with your current M27 processing would look better in my opinion. PS layers with a very soft edge mask would likely do it. 🙂

Alan

[tomato]

Yes, I see what you mean. I might also try not minimising the stars so much, they are there, after all.

[ollypenrice]

Of course, if you were only to kick the PI habit and post process in Ps, it would be so much easier... 👹

With the subdued inner nebula this is remarkably deep and informative.  In the past, the outer nebulosity was strictly narrowband. I think this is a nice image and remarkable for the FL.

Olly

[Mr Spock]

Lovely deep image 👍 The re-process of the core is especially nice.

[symmetal]

My processing of the Cocoon Nebula using SXT seemed to work well even though the star density is similar to your M27. Whether this being RGB gave more information to SXT to work with I don't know. 🤔

Neutralizing the background colour cast should also help your image.  🙂

Alan

[tomato]

Thanks for the feedback, and true to form my 'Final Rendition' has now undergone two iterations...

[Sunshine]

I love it! it is wonderful!

[windjammer]

>>that an 11" RASA might be a candidate for the elusive imaging scope all rounder,

I think you might be almost there with your 8".  I am tempted.   V impressive all things considered - an almighty crop!  

re final, final, on my monitor I think I prefer V-2!  Its a little softer and more natural.

Simon

[symmetal]

I like your latest one a lot.😊 Having the stars more noticeable shows that areas where the stars are denser are the areas that were made lighter by SXT, but the actual stars being present hides this effect to some degree. M27's 'wings' stand out more too now.

I'll have to try this with my RASA 11 to see what the extra focal length brings, as well as adding some SII for full SHO. The main advantage of the RASA 11 I think, is the ability to easily use a mono camera with a filter drawer, as it has 72.8mm of back focus to play with if you use the Baader UFC system, (necessary for full frame cameras), or 55.0mm back focus using the Celestron M48 adapter. It does mean getting 'fast' narrowband filters though which aren't cheap in 2" size, being £620 each for the Astronomik ones.

@windjammer There may still be an issue with recently made RASA 8 scopes, with the mirror edge causing large asymmetric flares on brighter stars. I had to return three RASA 8 scopes a year or so ago, because of this and Celestron ended up returning their entire stock back to China to be fixed. FLO are still listing 90 to 120 delivery as has been the case for the last year, so it's worth checking the latest situation with FLO. Because of the hassle I had Celestron, along with FLO, offered me a RASA 11 at a reduced price which I was happy to accept. 🙂 

Alan

[tomato]

12 hours ago, windjammer said:

>>that an 11" RASA might be a candidate for the elusive imaging scope all rounder,

I think you might be almost there with your 8".  I am tempted.   V impressive all things considered - an almighty crop!  

re final, final, on my monitor I think I prefer V-2!  Its a little softer and more natural.

Simon

Yes, the background is more even but I think the image is a bit 'harder' and the faintest nebulosity has suffered as a consequence. There might be a 3rd iteration...

[tomato]

I posted this 3rd and for now final iteration just after the first abortive SGL reset and realised it got lost in the ether after Grant's second go. I think more data is required to get it much better, I also have seen quite a bit of Ha nebulosity in the vicinity of M27 from some SY135 data captured at the same time as the RASA8 image, so it might be tricky to get an even background when pushing the faint PN outer nebulosity. At least, that's my excuse.

[gorann]

A very nice image Steve!

Gary Imm just posted this comparison of galaxy shots he has done with his EdgeHD 11 and RASA 11, and arguably (and maybe surprisingly) you could say the RASA may wins!

https://www.astrobin.com/i0cygy/

I have been tempted to get a RASA 11 but could not defend the cost, and now I found up a cheap (450 GBP) second hand Hyperstar v.4 that I can attach to an EdgeHD 11 that I have had for a while but rarely used. I will connect it to my IMX571mono (a QHY268M) with a filter slider and if I manage to collimate it (the big IF with Hyperstar) I will compare it with my dual RASA8 rig when astrodarkness comes back late August. Hopefully it can work in concert with my dual RASA8s (but on a separate rig) to collect pure mono NB data.

Edited July 6, 2023 by gorann