Given I had my new UV/IR Cut filter in the scope and another moonless night in what was becoming an week of clear skies, I decided to grab something a little easier than my last imaging session of the Witches Head. The choice given what was available and the limited Focal Length of my system was down to the Pleiades, Andromeda Galaxy or the Triangulum Galaxy. Having not taken Triangulum before that target was 'locked and loaded' into NINA's advanced sequencer.
Night of the 21st January 2023 and this was the last night in a run of I think 6 clear ones. Triangulum's formal Messier title of M33 is one of only two single galaxies that I tend to point my scope at. I don't have the long focal lengths required for these very distant objects. However, Triangulum presents a near face on view and it's only 2.7 Million Light Years away so lets give it a go. According to Nina's Framing Wizard there was a good chance of this being a worthwhile target. I knew from my experience of the DSLR without a Dual Band filter than 2 minutes was about as good as I could do before being fogged out with light pollution, so lots of 2 minutes exposures it was.
The galaxy gets its name from the Triangulum constellation in which is appears to sit (obviously this is a line of sight coincidence). Under very dark skies it is meant to be visible. In fact for the top 3 classes, M33 is one of the stated objects that should be visible. `It is just a little further off than Andromeda, 3.2 million light years compared to 2.5 million light year and is the 3rd largest in our local group (behind the Milky Way & Andromeda)
It is about 60% of the size of the Milky Way, (about 61000 Light Years across). Galaxies are given categories that describe their shape, Triangulum is a disk shaped spiral galaxy. We see it quite nicely tilted towards us by 54º so we get a good view of its structure. There is some suggestion that in the very distant past this galaxy collided with the Andromeda Galaxy, there is evidence of streams of Hydrogen and some stars that link the two.
Capture
Jan 21st 2023
As this is a broadband target I caught it with the UV/IR Cut filter at 120s exposure (limited by light pollution in my area). Started imaging at Astronomical dark 6pm until 11:15 pm - when light cloud started appearing.
117 * 2m Exposures = 3h54m
Capture using my new IR/UV Cut filter with the ZWO ASI533MC Pro camera running at -10º, gain 100 Offset 40.
I was able to use a 120s library file for a master dark I had taken for an earlier project.
30 Flats and 30 Darkflats were also taken - exposure to get a 50% histogram of 0.8s.
Pre-Processing
After registration 100 Lights available
Removed for FWHM > 4.9
Removed wFWHM > 6
Leaving 100 of 117, 100*2m = 3h20m of exposure time
Post Processing
Performed normal Siril Post Processing:-
A moderate cropt to focus very much on the galaxy
Deconvolution (0.9).
Photometric Colour Calibration
Asinh Stretch - 3 iterations with stretches of (15,5,3)
Used Photoshop to perform a levels and curve stretches - this was a gentle procedure to get to a first gently stretch
Photoshop Processing
Once this initial stretching was complete I continued in PS with the following-
Raw - Highlights and Contrast
Raw - Texture
Raw - Clarity
Raw - Noise Reduction, small Noise and small detail enhancement
Raw - Shadow, small Sat, Vibrancy
Created Saved the overall workflow as a Tiff then exported final image to JPG and version for my Social feeds and Astrobin.
Results
More exposure time necessary and perhaps using the Dual-band L-Enhance filter would be useful in bringing out some of the nebulous regions in the arms. I am quite happy with some of the texture I managed to show in the arms and using just UV/IR Cut is always a challenge from my back garden.
Anyway - an exhausting week of imaging, I believe looking at the weather forecast that I have some enforced downtime for the upcoming week.
Clear Skies folks.
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