M 74 - ASI2600MC - EdgeHD 9.25" - CEM60 - L+DuoNB - 22 Hours (Rowland Archer)

M 74 - ASI2600MC - EdgeHD 9.25" - CEM60 - L+DuoNB - 22 Hours

M 74 is a gorgeous face-on spiral galaxy in Pisces, estimated to be about 32MLY from Earth. With lots of structure and symmetry, it's a fun target to shoot and process.

I captured it with the EdgeHD 9.25" SCT with a focal reducer giving a FL of 1635mm and I used the ASI2600MC color camera. Most of the time was shot with a UV/IR L filter, augmented with the STC duoNB filter to pick up the nice Ha knots so prevalent in the spiral arms.

Calibration was done with gess and Siril.
Preprocessing with WBPP - I ran an experiment with WBPP and FBPP on the same data. The results were almost imperceptibly different. WBPP did a better job giving a smooth background since quite a few of the frames were shot with a different PA due to an adjustment error. But the cropped portion shown here, with a zoom level of 1:2 focused on the galaxy, was very similar between the two. The big difference - WBPP took a little over 4X as long to run, over 6 hours compared to 1.5 for FBPP.

From there it was the usual PI workflow - crop, GradX, SPCC, BlurXT and NoiseXT. I tried using StarXT on the duoNB master but it killed most of the Ha knots as well so I didn't use that in this process. I used SetiAstro's StatisticalStretch on both masters, then combined them with the CombineHawithRGB script. HDRMT with Gaussian 9, LHE at 150, and a bit of curves for contrast and saturation. I transferred the TIFF result to 3D LUT Creator which does many things but its coolest feature is a click and drag selective color manipulation which I used to bring up the blue in the arms and the magenta in the Ha knots.

Comments and critique welcome. Thanks for having a look.

Original
Final
B

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Status	Advanced success
Started	...
PixInsight job	ASAOZJO3ZOMTHY4XUKG90K9ESMV7LCCE
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	01h36m42s.940
RA (top/left)	01h37m18s.219
RA (top/right)	01h36m54s.665
RA (bottom/right)	01h36m05s.830
RA (bottom/left)	01h36m29s.441

Dec (center)	+15°46′59″.99
Dec (top/left)	+15°42′08″.55
Dec (top/right)	+15°56′30″.30
Dec (bottom/right)	+15°51′50″.83
Dec (bottom/left)	+15°37′29″.57

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