sh2-108/IC1318/LBN238 (c-sho)

[ramdom]

Also includes NGC6910.

Total integration: 1942 minutes/32.4 hours (98 x 300s or 11.43h for Ha + 96 x 300s or 11.20h for O3 + 84 x 300s or 9.80h for S2).

Cameras: QHY294M (11mp mono) CMOS cooled to -15 degrees C.

Telescopes: Stellarvue SV70T triplet apochromat refractor @ f/4.8.

Reducers: SFFR70-APO (0.8x).

Mount: Paramount MyT.

Filters: 1.25" Astrodon 5nm Ha, 3nm O3, and 3nm S2.

Software: TheSkyX Pro, SharpCap, PixInsight, Topaz Studio 2.

 

Inline images with reduced quality uploaded to the forum. Full resolution images are available at https://www.astrobin.com/nm6fwk/ and of the main image at http://ram.org/images/space/scope/1.4.4.7/sh2-108_c_lsho_588m+686m+672m_1942m_33h.jpg

 

sh2-108 is often called the Gamma Cygni (Sadr) nebula or even Sadr region because of the foreground appearance of the supergiant star. However, this is an optical illusion: this nebula lies far beyond Gamma Cygni/Sadr in the depths of the Cygnus X complex of star formation regions. Sadr itself lies at a distance of ~1500 light years.

 

The small open cluster of stars above Sadr in the top middle is NGC6910.  This cluster however may be located within the nebula itself, as it is at a similar distance of ~3700 light years beyond the galactic Great Rift (the dark band of interstellar clouds of cosmic dust obscuring the middle of the Milky Way, including the stellar association Cygnus OB9, whose core cluster comprises NGC6910). Apparently the dust in front dims the light from the open cluster by more than one magnitude. Still, this 2.2 magnitude object resembling a butterfly shape (and is sometimes also called that) shows off a number of both emission and dark nebulae.

 

This is my first image after a long hiatus, since 2022 was very busy for me.  Thankfully, sh2-108 was a relatively straight-forward target, very bright even though I put in some good time on it which helps with noise control and also weighting of images. Even though I've been busy with sciencing the past summer, the weather was not cooperative: there was lot of rain and clouds and the seeing was terrible. So having a lot of exposures helps with improving quality.  I avoided doing this target in the past because there's a much larger context that is beautiful and maybe best done with a wide field lens or as a composite but given my time availability, I chose to do the path of least resistance here.

 

The first image (https://www.astrobin.com/nm6fwk/A/) is a Ha only image. The second (https://www.astrobin.com/nm6fwk/B/) is the PixInsight processed image, quite minimal, using the Ha for the L image. I tried a composite L from the mono S2, Ha, and O3 data but Sadr really showed up brightly (due to the O3 signal) and decided this was the better route. I also further processed the PixInsight image in TopazStudio 2 (https://www.astrobin.com/nm6fwk/C/ - minimal and https://www.astrobin.com/nm6fwk/D/). As usual, the processing in C and D looks aesthetically great from far away but if you zoom in, you can see the compromises made to achieve the better look.  I am not sure which is better and if you have thoughts on this, please comment.  My other image of the Jellyfish Nebula with this type of processing won the 2021 Wiki Science Competition international prize in the astronomy category (https://en.wikipedia.org/wiki/Wikipedia:Wiki_Science_Competition_2019_in_the_United_States/Full_results#General). So obviously some people like it and it may well be that the only people that zoom on these images are fellow astrophotographers.

 

As always, thanks for looking!

 

--Ram

PS: Even though I lurk here, I've been away for a long time - life has kept me busy and I only managed to gather data for three images this past summer. I'm glad to be back, missed you all, and best wishes for a happy new year!

 

[tooth_dr]

Hi Ram, had a look on astrobin there, version A looks natural.  But for me personally you have went too far with the images BCD for my taste, and introduced processing artefacts that detract from the image detail, sorry!

[ramdom]

No need to apologise! But A is only Ha data and B is only PixInsight - very light and standard processing (it's basically what was done for A for S2 and O3 also, and then these are the only steps I've done for this image: ChannelCombination, CorrectMagentaStars, SCNR, very slight CurvesTransformation, DynamicCrop - I'm only saying this to illustrate how little this is since I do the vast majority of my colour processing in Topaz Studio 2 now). Only the Topaz Studio 2 versions (C and D) are more extensively processed but I sincerely appreciate your feedback! 

I've also found it interesting that  at least among people I know, most APers tend to prefer the less processed versions (B in this case). This includes me, we're the only ones who zoom in and look around, etc. But laypeople like my wife, daughter, etc. all prefer the extensively processed Topaz Studio 2 (D) version (which I agree does introduce artifacts).

--Ram