NGC7635 Bubble Nebula revisited in HaRGB

[Filroden]

After an unprecedented third clear night, I gathered more Ha subs of the Bubble plus LRGB data. Processing this has not been a pleasure. The gradients in my RGB data are terrible and this area has little background to pin DBE against! I discarded the 56 x 120s of L data as it added nothing to the final image. So this is a combination of the RGB with Ha 33% mixed into R and the synthetic L channel.

Taken on the evenings of 18 & 19 November 2017 .

Equipment: Skywatcher Esprit 80 with the ZWO 1600MM-C using an Astrodon 3nm Ha filter and ZWO RGB filters mounted on the AVX with OAG guiding

Exposures: 40 x 240s of Ha and 20 x 120s each of RGB at unity gain

Processed: Pixinsight and Photoshop

Latest version:

Original image:

Original Ha image posted here using 20 x 240s subs:

 

[toxic]

very nice Ken i like it a lot

[tooth_dr]

Very good Filroden, a lovely rendition of an old favourite. What is that nebula to the right of the bubble?

[Filroden]

9 hours ago, tooth_dr said:

Very good Filroden, a lovely rendition of an old favourite. What is that nebula to the right of the bubble?

Thank you. It is NGC 7538. It’s the brightest area of Ha in that image.

 

[Guest]

I've found this one of the most unrewarding objects to image but you've  made a good attempt at it.

David

 

[Filroden]

13 minutes ago, David_L said:

I've found this one of the most unrewarding objects to image but you've  made a good attempt at it.

David

 

Thank you. I’ve actually seen some stunning images of the area, though usually with a much larger field of view. It’s a lot like Cygnus - almost too much going on in the area to frame things well.

[Allinthehead]

That's very nicely done. It looks a little dark on my screen, how did your histogram look?

[Filroden]

18 minutes ago, Allinthehead said:

That's very nicely done. It looks a little dark on my screen, how did your histogram look?

Something more like this?

[Allinthehead]

Yes that looks great from here. How did you brighten it? I see you use PI and PS

[Filroden]

15 minutes ago, Allinthehead said:

Yes that looks great from here. How did you brighten it? I see you use PI and PS

I used the Background Enhancement script in Pi, added a little more of the Ha into the image and then, in Ps, lifted the curve to give a background of about 19/19/19 and then applied a curve to brighten the image some more. My screen is obviously a lot brighter as this looked quite pale on my screen.

[Filroden]

PixInsight has included a new script that tries to improve contrast at a local level. I hadn't enabled it so had not realised it was there. I've given it a shot on my Ha image of the bubble and it did seem to improve local contrast and draw out some of the more subtle detail in the surrounding nebula. However, when I've blended it back into the RGB I'm not sure if it's better than the previous version. Any preferences?

[Barry-Wilson]

Sumptuous deep reds and star colouring Ken - I really like it , well done and good job.

[Filroden]

23 minutes ago, Barry-Wilson said:

Sumptuous deep reds and star colouring Ken - I really like it , well done and good job.

Thanks Barry. It's been a difficult one to process but worth it for the final result.

[Allinthehead]

I like that last version even more.

[StargeezerTim]

Lovely. I love how Ha adds punch and depth to images.

[tooth_dr]

Last version is excellent, really worth all the effort processing it.

[Filroden]

23 hours ago, Allinthehead said:

I like that last version even more.

Thanks. Me too. It's now my desktop and I'm wondering whether it will print nicely!

1 hour ago, StargeezerTim said:

Lovely. I love how Ha adds punch and depth to images.

Yes. I did capture almost 2 hours of lum data but it destroyed the RGB through star bloat. I think if I capture L again, I need much shorter exposures. But the Ha in this area is so strong that it takes the colour really well.

17 minutes ago, tooth_dr said:

Last version is excellent, really worth all the effort processing it.

Thank you. I think I enjoy the processing almost as much as the gathering (probably more, if I'm honest).

[Filroden]

Well, I have the day off work and nothing better to do than start again. I've completely reprocessed my Bubble data and included the 56 x 120s L subs which I improved by using LocalNormalisation before integration to help remove changing sky conditions over the imaging sessions, and also through deconvolution (maybe too much?). This is a very different result to earlier images. I've done most of the blending in Photoshop rather than PixInsight. It's lost its deep red but there is much more colour variation throughout the nebulae.

Exposures: 40 x 240s Ha, (new) 56 x 120s of L and 20 x 120s each of RGB all at unity gain

[The Admiral]

Ken I think I prefer this process. Sumptuous reds they may have been in the previous process, but if I'm honest I found it a bit flat. This one shows more variation and the better for it. The bubble is also more emphatic.

Ian

[Filroden]

14 minutes ago, The Admiral said:

Ken I think I prefer this process. Sumptuous reds they may have been in the previous process, but if I'm honest I found it a bit flat. This one shows more variation and the better for it. The bubble is also more emphatic.

Ian

Thanks Ian. I agree though the reds did look good on the 4K TV screen!