Tulip Sh2-101 Cygnus Star Cloud / Tulip Nebula HaRGB

[x6gas]

I've been banging away at Sh2-101, the Tulip Nebula in Cygnus, for the last few clear nights shaking down my new CEM40 mount.  Initially I imaged this with my Tak FSQ85 but I wanted to see how the mount handled my TS130 Super Apo.  Focal length is still only 860mm and the whole rig is 12kg (26.5lbs) i.e. at 2/3rds of the rated (usually interpreted as for visual) payload capacity so this wasn't pushing the mount too hard but I didn't lose a sub to bad guiding over the three nights I captured this data.

My processing skills are coming back slowly but it feels I've still got a long way to go... mostly processed in PixInsight, which I am still learning, with some tweakery in PS.  On the HaRGB version I ended up adding the Ha as a luminance layer partly to increase contrast but partly to make the nebula pinker (didn't think I'd ever be doing that!) but the original deep red just didn't look right to me for this target...

Kit

Mount: CEM40; Camera: Atik 460ex; Filters: Atik EFW2 with unmounted Astrodons (Ha 5nm); Guiding: Atik OAG, QHY 5II

Data

Ha: 18 x 600s; RGB: 40 x 180s of each channel for a total integration time of 9 hours.  No calibrations frames at all, by the way.  The low noise of the Atik 460 means that I could get away with just using Cosmetic Correction in PI without darks, vignetting wasn't a problem (no field correction in this process) and my bias frames are over-correcting for reasons I haven't fathomed yet!

Anyway, Ha, RGB, and HaRGB versions and just for fun an Ha/OIII/SII version with the Ha data from the TS130 used as luminance over the colour process from the FSQ85 data.  Must admit that I like the RGB version as it shows off the lovely mix of blue and red stars.  The nebula is pretty bright in Ha and the HaRGB version kinda washes out the star field...

 

As usual comments and advice welcome.

Thanks for looking and clear skies.

Edited October 26, 2019 by x6gas
added the rather muddy looking Hubble palette

[Adreneline]

My personal favourite is the last one - it seems to have more depth and I really like the light blue contrast with the dusty-brown surrounding nebula.

You say it Ha/OIII/SII - was it 100% of each assigned to RGB using PixelMath or ChannelCombination?

Thanks for sharing.

Adrian

[x6gas]

11 hours ago, Adreneline said:

My personal favourite is the last one - it seems to have more depth and I really like the light blue contrast with the dusty-brown surrounding nebula.

You say it Ha/OIII/SII - was it 100% of each assigned to RGB using PixelMath or ChannelCombination?

Thanks for sharing.

Adrian

Thanks for the comment Adrian.  I agree that you get much more depth from the OIII and SII signal in the nebula itself.  I'm not very keen on the muddy brown in here though.  I have some OIII data from the TS130 and may try to add some SII to do a full Hubble using that data.

The version above is a real hash job to be honest.  I created the original Hubble version using the FSQ85 data which obviously was a wider field of view and different pixel scale.  That was processed in PI and, as you suggest, I assigned the narrowband data using ChannelCombination (and used the new narrowband PhotometricColorCalibration to get colour balance).  Then I matched that data to the new Ha using Registar (though I actually did that on a first quick process of the Ha which is why there are some artefacts around the edge that I haven't cropped out).  The Ha was then pasted over the colour data as a Luminance layer at full strength.  It came out better than I expected so I will go back and do a proper job at this image scale with a full 6 filter process.

Thanks again, Ian

[Chris]

That really is a super Apo. Look how tight the stars are! Well done on a great set of images

[pete_l]

13 hours ago, x6gas said:

Initially I imaged this with my Tak FSQ85 but I wanted to see how the mount handled my TS130 Super Apo. 

Can we have a shoot-out, please?

A single, unprocessed sub from each of these scopes. Side by side. It would be great to see how they compare

[x6gas]

Thanks Chris.

Yes I must admit it's a lovely scope - extremely well colour corrected, reasonably fast at f/6.6 and no vices; a Riccardi reducer gets you to 645mm f/l and f/5 so it's pretty versatile too.  TS don't do this model anymore, sadly.  The imaging scale with this set up is 1.09"/pixel and PHD2 was reporting an overall RMS error of ~0.4" for each session.  No deconvolution or other star shaping done to this data but the images I've posted here are downscaled to be 1200px high (so downscaled by a factor of about 2) and then I reduced the resolution in the post further.  PI reports FWHM of 2.667 and eccentricity of 0.601 on the Ha data so the eccentricity could be better; I think the focus was a bit off for some of the subs...

Cheers, Ian

Edited October 27, 2019 by x6gas
added PHD graph

[x6gas]

18 minutes ago, pete_l said:

Can we have a shoot-out, please?

A single, unprocessed sub from each of these scopes. Side by side. It would be great to see how they compare

Sure thing, though obviously these were taken on different nights under different conditions...

FSQ85_Sh2-101_001_600_Ha.fit

TS130_Sh2-101_001_600_Ha.fit

 

[Adreneline]

59 minutes ago, x6gas said:

I'm not very keen on the muddy brown in here though.

Haha! Well that's a good point although I can't help but feel that space is a pretty dusty place and muddy brown always seems to fit the bill to me.

 

 

[x6gas]

15 minutes ago, Adreneline said:

Haha! Well that's a good point although I can't help but feel that space is a pretty dusty place and muddy brown always seems to fit the bill to me.

 

 

Well, yeah, but let's not forget that what looks muddy brown in that image is actually glowing red!