Triangulum galaxy M33/NGC598 (c-lrgbhos)

[ramdom]

• Total integration: 458 minutes/7.64 hours (*77 x 120s for OSC + **139 x 60s + 10 x 120s for L + 13 x 300s for Ha + 8 x 300s for O3 + 8 x 300s for S2).
• Cameras: *QHY247C (24mp OSC) and **QHY163M (16mp mono) CMOS cooled to -15 and -20 degrees C.
• Telescopes: Takahashi *FC100DF and **FS128N Steinheil fluorite doublet apochromat refractors @ f/4.9 and f/5.7.
• Reducers: Takahashi *FC-35 (0.66x) and **TOA/FS 130-R (0.7x).
• Mount: Paramount MyT.
• Filters: *2" Baader UV-IR-Cut and **1.25" Astrodon 5nm Ha, 3nm O3, 3nm S2.
• Software: TheSkyX Pro, Sharpcap, PixInsight, Photoshop CC. 

Triangulum is yet another member of our local group of galaxies, about three million light years away and is the third largest behind our own Milky Way and Andromeda, one of the distant permanent objects that can be seen with just your naked eye under the right conditions.

Imaging this galaxy ended up being a complicated process. I collected all the data that went into one of the final images over a couple of years. I had earlier collected the luminance and narrowband data on my Takahashi FS128N with the mono QHY163M camera in 2017 but I decided to redo this one in OSC with the colour QHY247C camera and the FC100DF tube. I then went about creating an image that combined all of the collected data by first creating a synthetic luminance channel which combined the luminance data from both the colour and mono cameras, then created a new LRGB image combining this with the separated red, blue and green channels and then added the Ha, O3, and S2 data to this image at a 80:20 ratio using PixelMath.

The great but sometimes frustrating aspect of astrophotography is that there are so many ways to produce a "final" image.  I find the variant without the narrowband data and just only with mono (L) data just as aesthetically pleasing (and it is interesting to observe the differences). In addition I tried out different weightings for the channel combinations and also different approaches for combination including PixInsight's NBRGB combination script. At this point, this is just one of the few choices among what I considered aesthetically pleasing and also reasonably accurate in terms of representing the data. Short of combining all the respective channels, I ended up doing little post processing for now.

Normally I've been tending towards combining RGB channels in linear form and then processing them further but this time I created the final "look" of each channel as I wanted it and just combined them which locks you in with earlier choices. This can be both good and bad, since as I write above, there are many branch points and they largely seem to produce interesting results. To this end, I also put up the synthetic LRGB only image (containing all the luminance and OSC data) and also the complete luminance image for comparison:

https://www.astrobin.com/418204/B/

https://www.astrobin.com/418204/C/

As always, thanks for looking!

--Ram

PS: As many of you may already know, the prominent pink blob on the top right hand side is one of the nebulae in this galaxy. I always want to travel in space like Star Trek nd go from sight to sight in our galaxy or even galaxy to galaxy and astronomy is one of the ways I can come close to achieving this dream in my lifetime but I was looking this up and was blown away by the sheer scale of things. The pink blob imaged through the HST looks like this: https://en.wikipedia.org/wiki/Triangulum_Galaxy#/media/File:Nursery_of_New_Stars_-_GPN-2000-000972.jpg which is a large nebula in its own right and at its core is a cluster of about 200 stars each of which is as many as 15-60 times bigger than our own sun (recall that 1.3 million Earths can fit in our sun).

And then you can think about the scale on the other side (how many atoms are present in a body, how many subatomic particles, etc.). It's amazing we're at this particular scale asking these questions and taking snapshots of the upper end and doing simulations of the lower end...

[assouptro]

Great image and write up. You’ve  reminded me why I love this ridiculous hobby!

Oh, to travel among the stars!!