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For today’s observation blog, here is our take of Messier 108 (also known as the Surfboard Galaxy or NGC 3556) taken from Al Sadeem Observatory on April 20, 2018, using RC8″ Telescope, EQ6 pro mount, and modified Canon EOS 5D Mark IV.

Messier 108 is a barred spiral galaxy located in the well-known constellation Ursa Major (the big bear). Its name was derived from its appearance of a slightly inclined elliptical streak of light with no distinct bulge at the center (core) and loosely wound spiral arms, resembling a surfboard. Discovered by French astronomer on February 19, 1781, it lies about 45.9 million light-years away from Earth with an apparent magnitude of +10.7, one of the brightest galaxies within the Ursa Major galaxy cluster. It spans around 110,000 light-years across space and it was found out through spectroscopic measurements that it is moving away from us (redshift) at the speed of 699km/s.

Several interesting observations were recorded by astronomers from this galaxy over the years after its discovery. On January 23, 1969, a type II supernova was observed within the galaxy, designated as SN 1969B. 83 X-ray sources detected by the Chandra X-ray Observatory suggest that its supermassive black hole, about 24 million times the mass of the Sun, actively accretes stellar material near the center of Messier 108. It was found to contain shells of expanding gas which either generated from stellar formations outbursts and supernova explosions, radio jets or infall of gas from outside the galaxy.

In the night sky, Messier 108 lies about 1.5 degrees from the pointer star Merak. Using a 3-inch telescope, it would appear as a faint straight streak of light, sharing the same field of view with M109 (The Owl Nebula) situated 48 arc-minutes from M108, and more detail will be revealed as telescope aperture increases. Springtime (March-May) is the best season to view the Surfboard Galaxy. It will be circumpolar (neither rise nor set) in the sky at areas 35 north of the equator and above.

Finder Chart for M108 (Source: freestarcharts)


Messier 108: Surfboard Galaxy

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