NGC7023 (Iris nebula) up close and personal

[swag72]

Here is something that as an imager I know shouldn't be done - Imaging at f10 with a pixel size in the camera of 3.4um!!! Madness, utter madness!

This Iris took a while to get and still I am afraid to say uses a synthetic green channel. My green channel attempts were thwarted at every turn by the weather. Whether a proper green channel would make a difference I'll never know!!!

I welcome comments, good bad and indifferent as I really am still getting to grips with this long focal length imaging and as for LRGB - I can literally count on one hand how many of those I have done!

Details

M: Avalon Linear Fast reverse

T: Celestron C9.25

C: QSI690 WSG, Baader filters and an SXAO unit

92x300s 2x2 Lum

58x300s 1x1 Lum

50x60s 2x2 Lum

17x100s 2x2 Red

64x100s 2x2 Blue

Totalling 17h 16m 40s

You can see a larger version here http://swagastro.weebly.com/uploads/2/3/3/7/23377322/upload.jpg

[Ewan]

Nothing wrong with that image scale Sara & it looks ok.

F10 is more forgiving with your setup i would imagine, i am glad i haven't got to attempt that anymore with my cg5.

A lot of hours you put into each target, each & everytime, great shot.

[Gina]

Lovely   I think many people are put off trying things by others saying "that won't work" etc.  I say "try it - you'll never know for sure if you don't".  It's only by people trying things thought to be impossible that human knowledge is progressed.  But I think most on here will know my philosophy by now

[Epicycle]

That's great Sara. One minor suggestion, but most likely you tried already, is that perhaps the image could take a bit more sharpening; to my eyes, it looks just a bit soft.

Synthetic green vs real green is something I often wonder. For example the data coming from DSS-II only has red and blue filters and people still produce amazing

images from that data via a synthetic green (e.g. http://apod.nasa.gov/apod/ap140404.html).

E.

[julianr]

That's great Sara you don't often see the iris at this scale and nicely processed. Loads of detail in there no doubt helped by all the time spent on it like the colours

Sent from my GT-I9300 using Xparent Skyblue Tapatalk 2

[Barry-Wilson]

The scale reveals the centre detail well, however, I agree with Epicycle it does appear soft.  Is that a product of the sampling (re your other thread) do you think?  Lovely colouring, as always, invites and draws your eye to the depths!

Barry

[swag72]

Thanks for looking and commenting. This one has been a long time coming as it's sat on my PC for about 2 weeks while I wondered whether it was good enough. I added extra luminance, the sharper stuff and it did make a difference, previous to that it was even softer. I really have sharpened it as far as I felt it could take it.

Perhaps there is a reason why people say this sort of speed and under sampling shouldn't work and maybe it's time to accept this. Mmm, back off to the drawing board then, no good if the image is soft.

[Epicycle]

How did the luminance respond to deconvolution? At that pixel scale decon should help a lot.

Btw, are you finding the SX AO unit makes a big difference?

Cheers

E.

[swag72]

I think and believe that the AO unit is helping! I've not done a comparison with it on and off. If I do, then people will have to promise not to get all mathematical on me! 

[swag72]

Many thanks to Ewan, this has been tightened up a little more now. I think it's time to put this one to bed!!

[ChrisLX200]

That's a lovely image Sara, fantastic colours.

ChrisH

[swag72]

Thanks Chris. Makes a difference eh?

[AndyUK]

Yes...  That certainly makes a difference !  This is an excellent image (well up to your usual "house standard"), especially given that it's at such a relatively extreme focal length.  I've always wondered what the centre of the Iris looks like - In my past attempts at getting the Iris, this is the area that's always ended up being totally burnt out...

[swag72]

Cheers Andy. There's not masses of images out there of the Iris that aren't wide field.

[ChrisLX200]

I don't recall seeing any as close up as yours   Your results do make me want to try with my 10" LX200 but I don't think that is optically as good as the 9.25 Celestron, but still worth a shot perhaps.

ChrisH

[ollypenrice]

Sorry, but what do people want? Blood? Let's ask ourselves how many times we get this close to the Iris. Soft? Sure, compared to the Hubble. 

Using a TEC140 with about a metre of FL I was pretty darned pleased with my Iris but this has way, way more core detail. Sara isn't using a 20 inch Plane Wave on a Paramount, folks.

I feel that, of the two versions, a middle ground might be best because a hint of 'software sharpening' is creeping into the look, but not too much. Only rarely do we catch that Ha region. Even less frequently do we it pinned down as we see it here.

A very small number of SGL imagers try for something really difficult and I'm not one of them. I work conservatively within the bounds of my kit, which is good kit. Sara is pushing the boat out. I'm pretty impressed.

Olly

[lensman57]

Hi Sara,

Your capture of the iris nebula is insprational, I feel like having a go at it with my Mak 127, as you have proved it is possible to image at such long FLs.

Regards,

A.G

[swag72]

Chees Chris, Olly and AG.

@Chris - Defintiely give it a go. People would have tried to talk me out of this for sure at f10 You just never know what is achievable.

@Olly - Thanks for your kind words. I guess I am trying to push the envelope with this scope!

@AG - While I may have proved that long focal length imaging is possible, it's worth remembering that it's not being done with a run of the mill mount. I'm not sure what mount you have, but certainly when I had my HEQ5 I'd never have considered it, it just wasn't up to it.

[ChrisLX200]

Chees Chris, Olly and AG.

@Chris - Defintiely give it a go. People would have tried to talk me out of this for sure at f10 You just never know what is achievable.

@Olly - Thanks for your kind words. I guess I am trying to push the envelope with this scope!

@AG - While I may have proved that long focal length imaging is possible, it's worth remembering that it's not being done with a run of the mill mount. I'm not sure what mount you have, but certainly when I had my HEQ5 I'd never have considered it, it just wasn't up to it.

Sara: Having used your Avalon for a while are you able to say the typical error (arc-sec) it produces when tracking with the 9.25?  I've seen Olly's recent data and it looks very tight indeed carrying the TEC140. I'm trying to figure the performance requirement necessary to produce an excellent image like you have there. My G11 is fine with the refractor on board but I don't know what I would get with the heavier SCT. I know, I should just try the thing and see...

ChrisH

[PhotoGav]

This is a wonderful image Sara. 'Time to put this one to bed'? I think it will sleep very well indeed, in fact I can hear it snoring contentedly already! Amazing what you are doing from your Spanish roof top obsy. I've just had a look at your website and watch out folks... On the way - The Bubble like you've never seen it before!!!

[swag72]

Sara: Having used your Avalon for a while are you able to say the typical error (arc-sec) it produces when tracking with the 9.25?  I've seen Olly's recent data and it looks very tight indeed carrying the TEC140. I'm trying to figure the performance requirement necessary to produce an excellent image like you have there. My G11 is fine with the refractor on board but I don't know what I would get with the heavier SCT. I know, I should just try the thing and see...

If the arc second error is that RMS figure - Then I get about 0.1 in both axis - But bear in mind that I am using an Active Optics unit as well, which should help things. Try what you have and see, you may be pleasantly surprised!

Thanks Gav - If this cloud would clear, then yes, there's a bubble on the way and something else that I've not added to the site yet as I've had friends to stay! I hope to put that on later.

[lensman57]

Chees Chris, Olly and AG.

@Chris - Defintiely give it a go. People would have tried to talk me out of this for sure at f10 You just never know what is achievable.

@Olly - Thanks for your kind words. I guess I am trying to push the envelope with this scope!

@AG - While I may have proved that long focal length imaging is possible, it's worth remembering that it's not being done with a run of the mill mount. I'm not sure what mount you have, but certainly when I had my HEQ5 I'd never have considered it, it just wasn't up to it.

Hi Sara,

I have done it once with my HEQ5Pro and the 127@ native FL. It didn't turn out too badly, nowhere near the quality that you are getting but it was a lot less integration time. Moy concernes were a) the lenght of the subs were not long enough to register enough signal and b} that the Mak on an HEQ5 has the finder shoe well to the left of the scope which makes the balance of the whole set up rather lopsided so perhaps that is why I didn't go beyond 900s subs. This is the link to the image, nothing to write home about but as they say in engineering it is a proof of concept. http://www.astrobin.com/96528/

Thanks again for a great image and best regards,

A.G