M109 is a magnitude 11 spiral galaxy in Ursa Major, located at the bottom of the "bowl" of the Big Dipper. It is one of the few barred spiral galaxies that can be observed with an 8-inch amateur telescope. It is about 46 million light-years away, and has a diameter in excess of 100,000 light-years. The galaxy shines with the light of 19 billion suns.
M109 was discovered by Mechain in 1781 or 1782. It was also viewed by Messier, but was not added to the Messier catalog until the twentieth century.
The constellation Ursa Major is a treasure trove of galaxies. The small galaxy in the upper right-hand corner of the frame is UGC 6923, a 14th magnitude irregular galaxy. The galaxy visible immediately below M109 is 15th magnitude UGC 6969, also an irregular galaxy. Finally, this image also recorded the very faint magnitude 16.8 spiral galaxy visible to the right of M109, which is UGC 6940. Ursa Major is also the home for other beautiful galaxies such as M81, M82, and M101.
This composite LRGB CCD image was taken from my backyard in Scottsdale, Arizona, over the course of two nights. In this image, north is to the left. An ST-8E CCD was used at prime focus on a Takahashi FCT-150 refractor at f7. The optical tube assembly was carried on a Takahashi NJP mount. The digital images were calibrated using MaxIm DL. The LRGB color composite was assembled using PhotoShop 7.0
M109 (NGC 3992)
Constellation: Ursa Major
RA: 11h 57m 45.0s Dec: +53d 21' 49"
January 1 & 2, 2003
Image by Sid Leach
Scottsdale, Arizona
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