M51 - Whirlpool Galaxy
Messier 51 or M51 (also designated NGC 5194/5) is a spiral galaxy in the constellation Canes Venatici. It has an apparent visual magnitude of 8.4 and its angular diameter is 11x7 arc-minutes. M51 lies at an estimated distance of 37 million light years. The Equinox 2000 coordinates are RA= 13h 30m, Dec= +47° 11´ which makes M51 best seen during the spring. The Messier Spring Star Chart shows the position of all Messier objects visible during that season. As one of the more famous objects in the Messier Catalog, it is commonly known as the Whirlpool Galaxy.
The image above shows the uncropped view of M51 and its companion galaxy NGC 5195 through the Takahashi E-180 Astrograph (North is up). A 3x enlargement of this image appears to the right.
For a higher magnification view of this galaxy using the ASA N12 Corrected Newtonian Astrograph, see M51 (ASA N12).
The Whirlpool Galaxy was discovered by Messier in 1773 and is one of the best known spiral galaxies. It was the first such object in which the spiral structure was observed by Lord Rosse in 1845. Its unusually pronounced spiral structure is due in part to the strong gravitational interaction with its companion galaxy NGC 5195. According to Stoyan et al. (2010), the distance of M51 is 26.8 million light years and its diameter is 87,000 light years.
For more information, see the Messier Catalog as well as specific entries for M51 in Wikipedia and SEDS.
Messier's Description of M51
January 11, 1774
`Very faint nebula, without stars, near the eye of the Northern Greyhound
[hunting dog], below the star Eta of 2nd magnitude of the tail of Ursa Major:
M. Messier discovered this nebula on October 13, 1773, while he was watching
the comet visible at that time. One cannot see this nebula without difficulties
with an simple refractor of 3.5 feet: Near it is a star of 8th magnitude.
M. Messier reported its position on the Chart of the Comet observed in 1773
and 1774. Memoirs of the Academy 1774, plate III.
It is double, each has a bright center, which are separated 4'35".
The two "atmospheres" touch each other, the one is even fainter than the
other. Reobserved several times.'
Technical Details
- Object: M51
- Other Names: NGC 5194/5, Whirlpool Galaxy
- Object Type: spiral galaxy
- Object Data: Apparent Magnitude = 8.4, Angular Size = 11x7 arc-minutes
- Object Position (Equinox 2000): RA= 13h 30m, Dec= +47° 11´, Constellation = Canes Venatici
- Date/Time: 2011 Apr 23 at 06:39 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: M51-01w.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.