Andromeda - M31 (2026)

It has been a while since I last imaged our closest large spiral galaxy neighbor Andromeda, or M31, so though it was a good time for revisit. Andromeda is considered our sister galaxy as it is believed to be roughly the same size as our own galaxy at approximately 150,000 light-years, however, size estimates of Andromeda and Milky Way vary a lot so it is not clear if it is larger or smaller. It is 2.5 million LY away and is expected to merge with our own galaxy in the next 5 to 10 billion years.

Several dense red knots are located on the outer spiral arms of Andromeda. These are star-forming hydrogen gas nebulae. The galaxy also has very prominent dust lanes between the spiral arms. Two prominent satellite galaxies M32, the bright blob above the galaxy plane, and M110, the bright blob below the plane, are clearly visible. M32 is a dwarf elliptical galaxy approximately 8,000 LY in diameter and M110 is a dwarf elliptical galaxy approximately 16,000 LY in diameter. 

The red areas surrounding Andromeda are hydrogen gas emission (Ha) clouds within our own galaxy that happen to be in the same direction. These gas clouds were recently discovered to be exceedingly faint. I was very interested in attempting to capture them but I had a limited field of view in CT so I waited until the move to NM where I had the whole nights for imaging. The almost 90 hours of exposure using the NBZ dualband filter was just enough to capture some of the hydrogen. 

For the Astro Peeps:

There is a very faint oxygen (OIII) emission arc which would be located in the upper left portion of my image, unfortunately, I was unable to pick it up with my setup. Much as I would have liked, I was not expecting to get any of the OIII with my NBZ filter. It is an older version where the bandpasses are about 10nm (Ha) and 12nm (OIII) - I suspect newer more narrow bandpass filters would be better suited for acquiring that data. Anyway, happy I obtained what I did!

Higher Quality:
https://www.astrobin.com/q9rt0l/?nc=collection&nce=712

Andromeda - M31 (2026)
Dates: 9-10, 10-1, 10-2, 10-4, 10-5, 10-6, 10-7, 10-8, 10-9, 10-12, 10-13, 10-14, 10-15, 10-16
Camera: ZWO ASI2600MC-Pro
Telescope: Askar FRA300 Pro
Barlow: None
Focal Length: 300mm
f/5
Focal Reducer: none
Mount: ZWO AM3
Filter Adaptor: ZWO Filter Drawer
Filter: Camera UV/IR, IDAS NBZ
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to a ZWO Mini guidescope
Exposure: UV/IR 364 x 90 (9h 6m), NBZ 1074 x 300 (89h 30m)
Gain: 100
Offset 20
Sensor Temp: 0 C
Processing: PixInsight, Photoshop, BlurXTerminator, StarXTerminator, NoiseXTerminator, GraXpert, Bill Blanshan Color Masks, Bill Blanshan Stretching, SETI Astro NB to RGB stars.

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