Messier 108 (also known as NGC 3556) is a barred spiral galaxy in the constellation Ursa Major. It was discovered by Pierre Méchain in 1781 or 1782. From the perspective of the Earth, this galaxy is seen almost edge-on.

This galaxy is an isolated member of the Ursa Major Cluster of galaxies in the Virgo supercluster. It has a morphological classification of type SBbc in the de Vaucouleurs system, which means it is a barred spiral galaxy with somewhat loosely wound arms. The maximum angular size of the galaxy in the optical band is 11′.1 × 4′.6, and it is inclined 75° to the line of sight.

This galaxy has an estimated mass of 125 billion times the mass of the Sun and includes about 290 ± 80 globular clusters. Examination of the distribution of neutral hydrogen in this galaxy shows shells of expanding gas extending for several kiloparsecs, known as H1 supershells. These may be driven by bursts of star formation activity, resulting in supernovae explosions. Alternatively they may result from an infall of gas from outside the galaxy or by radio jets.

Observations with the Chandra X-ray Observatory have identified 83 X-ray sources, including a source located at the nucleus. The brightest of these sources may be an intermediate-mass black hole that is accreting matter. The galaxy is also emitting a diffuse soft X-ray radiation within 10 kpc of the optical galaxy. The spectrum of the X-ray source at the core is consistent with an active galactic nucleus, but an examination with the Spitzer Space Telescope shows no indication of activity. The supermassive black hole at the core has an estimated mass equal to 24 million times the mass of the Sun. [Source: Wikipedia]

The image was captured with the new Celestron CGE Pro mount and the venerable Meade 12"LX200 SCT, using my Atik 383L+ mono at F7.16 (i.e. 2182mm FL). Astronomik's Luminance, Red, Green and Blue filters were used. All subs were taken at 1x1 bin, -10C. and 300s.

Image 2017 -- SGPro image capture software

Lum 300s: 28 subs (2.33 hr) on Mar 27th, 29th and 30th.

Red 300s: 19 subs (1.58 hr) on Mar 30th and 31st.

Green 300s: 20 subs (1.67 hr) on Mar 31st.

Blue 300s: 20 subs (1.67 hr) on Mar 31st.

Processing was done with PixInsight, following (for the most part) kayronjm's tutorial of Feb. 24th, 2013. Filter L was used to develop the Lum image. R, G and B were collected for the color mix. North is to the right (I think). This is a slight crop due to image misalignment due to plate solving variations and dithering.

This was the first image done with the CGE Pro mount. I'm still shaking the bugs out.

Pretty satisfied, although there should be some improvements I can make moving forward.