Messier 109 or M109 (also designated NGC 3992) is a barred spiral galaxy in the constellation Ursa Major. It has an apparent visual magnitude of 9.8 and its angular diameter is 7x4 arc-minutes. M109 lies at an estimated distance of 55 million light years. The Equinox 2000 coordinates are RA= 11h 57.6m, Dec= +53° 23´ which makes M109 best seen during the spring. The Messier Spring Star Chart shows the position of all Messier objects visible during that season.
The image above shows the uncropped view of M109 through the Takahashi E-180 Astrograph (North is up). The bright 2.43 magnitude star Phecda (Gamma Ursae Majoris) lies 0.7 degrees northwest of M109. A 3x enlargement of this image centered on M109 appears to the right.
According to Stoyan et al. (2010), the distance of M109 is 67.5 million light years and its diameter is 137,000 light years. Its estimated mass is 250 billion solar masses.
Messier's Description of M109
Méchain in his letter to Bernoulli, May 6, 1783)
`Page 265 No. 97 [M97]. A nebula near Beta in the Great Bear. Mr. Messier mentions, when indicating its position, two others, which I also have discovered and of which one is close to this one [M108], the other is situated close to Gamma in the Great Bear [this is M109], but I could not yet determine their positions.'
Messier added a position by hand which Owen Gingerich identified in 1953 as NGC 3992, which is now called M109)
- Object: M109
- Other Names: NGC 3992
- Object Type: barred spiral galaxy
- Object Data: Apparent Magnitude = 9.8, Angular Size = 7x4 arc-minutes
- Object Position (Equinox 2000): RA= 11h 57.6m, Dec= +53° 23´, Constellation = Ursa Major
- Date/Time: 2011 Apr 22 at 05:12 UTC
- Location: Bifrost Astronomical Observatory, Portal, AZ
- Mount: Astro-Physics 1200GTO
- Telescope: Takahashi Epsilon 180 Hyperbolic Astrograph
- Camera: Canon EOS 550D (Rebel T2i) (modified with a Baader UV/IR filter)
- Field of View: 1.70° x 2.56° at 1.7 arc-sec/pixel (web version: 10.0 arc-sec/pixel)
- Exposure: 4 x 300s, f/2.8, ISO 800
- File Name: M109-01w.jpg
- Processing (Adobe Camera Raw): Graduated Filter, Vignetting Correction, Noise Reduction, White Balance, Curves
- Processing (Photoshop CS5): Average Images, Curves, Noise Reduction
- Original Image Size: 3454 × 5179 pixels (17.9 MP); 11.5" x 17.3" @ 300 dpi
- Rights: Copyright 2011 by Fred Espenak. All Rights Reserved. See: Image Licensing.