DWB 111 The Propeller Nebula - Ha mono and HaRGB

[Barry-Wilson]

I have wanted to image this target for a couple of years now and I chose to mount my WO FLT132 rather than my widefield FSQ85 to help get closer to the target.  The Propeller sits within a much wider emission nebula complex in Cygnus and is often imaged with NB filters, regularly in the strong Ha signal and also in HST palette with the much fainter SII and OIII, such as Sara's corker from a couple of years ago, http://www.swagastro.com/dwb111.html.  The Propeller is also referred to as Simeis 57, and I have also read that this is its 'proper' catalogue designation and DWB 111 is incorrect; I'm not sure what is correct.  If anyone knows please chime in and explain.

I wanted to present the Propeller in a RGB format as well as the Ha mono and have captured first Ha over the last couple of weeks and then latterly the RGB data as the moon waned later in the twilght.  It is still quite early in the summer nebula season and I was quite anxious about the RGB data, especially the Blue channel as by the time 2:30/3:00am arrives the target is still some way from it's meridian, although it is relatively well placed high in the sky.  It is always good practice to capture the Blue channel at its highest to minimise the greater atmospheric dispersion and diffraction of the channel in comparison to the Red and Green - it can result in odd colourful ringing and flares in stars, especially bright ones.

So rather than align the RGB to my previously processed Ha during calibration and pre-processing, I made a straightforward change to my normal workflow and aligned the Red and Green to the Blue and then subsequently aligned the Ha to the RGB image: I don't know why I didn't think of this ages ago .  Age and infirmity perhaps?

Details:

• WO FLT132 at F5.6
• QSI683 wsg-8
• 10 Micron GM1000HPS
• Astrodon 5nm Ha; E-series Gen II RGB filters
• Captured with SGP and Processed in PI
• 15 x 1200s Ha; 21 x 300s each of RG&B
• Total integration 10.2hrs

Having viewed Bill Snyder's image on his informative website where he anotates and displays the individual channel images, http://billsnyderastrophotography.com/?page_id=4775, I'm not sure I will aim for the HST rendition at this image scale.  I am working on a few targets at once at the moment and the HST version may well be better placed in a wide field context as Sara and many other imagers have shown to great effect.  I'll wait until I swap scopes.

Many thanks for looking.

Firstly the Ha mono:

Secondly the HaRGB

 

 

 

Edited June 20, 2017 by Barry-Wilson
typo

[PhotoGav]

Excellent Barry. I very much like the HaRGB version - the colours are vibrant, but the processing subtle. 

[Allinthehead]

Very nice. lovely stars.

[swag72]

I like that HaRGB version Barry - The processing is very pleasing indeed Nice tight stars and good colour

[Barry-Wilson]

Thank you Gav, Allinthehead and Sara.

I was really pleased with the star colour - there is only a very small colour saturation boost in the linear stage before I carry out a masked stretch.

[wxsatuser]

Excellent Barry, I like the detail in the Ha and the processing.

[RichLD]

Lovely work Barry - I'm usually a mono lover but the HaRGB is fab and gets my vote!

[ollypenrice]

Nice, Barry, with a soft touch and great star colour.

Olly

[KoenDeBacker]

Wow nice Barry ! 

[Barry-Wilson]

21 hours ago, wxsatuser said:

Excellent Barry, I like the detail in the Ha and the processing.

Thank you Mike.  This is a very good Ha mono target and you can gently encourage plenty of detail to emerge.

Thank you Rich and KoenDeBacker.

9 hours ago, ollypenrice said:

Nice, Barry, with a soft touch and great star colour.

Olly

Cheers Olly.

I was absolutley staggered at the star colour.  Whilst I had a reasonable amount of data I thought it would have been impaired in the astro twilight.  But apparently not .

[swag72]

52 minutes ago, Barry-Wilson said:

....... I thought it would have been impaired in the astro twilight.  But apparently not .......

Judging by my efforts with globular clusters all taken in and around full moon, it would seem that stars are the great leveller when it comes to moonlight and lack of proper darkness!!! 

[steppenwolf]

I rather like this, especially the star colours and subtle processing - well done, Barry.

[Barry-Wilson]

37 minutes ago, swag72 said:

Judging by my efforts with globular clusters all taken in and around full moon, it would seem that stars are the great leveller when it comes to moonlight and lack of proper darkness!!! 

Agreed Sara.  I don't think I could have managed 600s subs (but I didn't try so can't be adamant) even though I was pointing many tens of degrees away from the moon.

29 minutes ago, steppenwolf said:

I rather like this, especially the star colours and subtle processing - well done, Barry.

Thanks Steve.

[Barry-Wilson]

46 minutes ago, swag72 said:

Judging by my efforts with globular clusters all taken in and around full moon, it would seem that stars are the great leveller when it comes to moonlight and lack of proper darkness!!! 

Just to illustrate Sara's and my experience, below is a jpeg of the RGB data (no Ha yet added) as it is immediately after a masked stretch in PixInsight.  To this point the individual channels have had MureDeNoise, then RGB combined, Dynamic Crop, DBE, Background Neutralisation, Colour Calibration, Repaired HSV Separation, very small saturation boost and then finally a Masked Stretch to take it non-Linear followed by SCNR.  I hope this gives a sense of the rich data.

Caveat: there is no guarantee that the moon won't spoil your data though .  But I would experiment if you are able to choose a target away from the moon when it is waning.  Remember "Rules are for the guidance of wise men and the obedience of fools".

[toxic]

well i got confused with that but i loved the images corkers they are Barry

[PatrickGilliland]

Nice work Barry - subtle yet engaging and deep, liking that.

[Barry-Wilson]

19 hours ago, toxic said:

well i got confused with that but i loved the images corkers they are Barry

Sorry Chris that was not my intention .  I simply meant that despite the seeming wisdom of not capturing RGB when the moon is about, the RGB data wasn't tainted with significant gradients or washed out contrast.  It is worth experimenting.

1 hour ago, PatrickGilliland said:

Nice work Barry - subtle yet engaging and deep, liking that.

Thanks Paddy.

[kirkster501]

Absolutely wonderful Barry. A sight to behold.  Uttterly magnificent.