Messier 5 or M5 (also designated NGC 5904) is a globular cluster in the constellation Serpens. It has an apparent visual magnitude of 5.6 and its angular diameter is 17.4 arc-minutes. M5 lies at an estimated distance of 24,500 light years. The Equinox 2000 coordinates are RA= 15h 18.6m, Dec= +02° 05´ which makes M5 best seen during the summer. The Messier Summer Star Chart shows the position of all Messier objects visible during that season.
The image above shows the uncropped view of M5 through the Takahashi E-180 Astrograph (North is up). A 3x enlargement of this image appears to the right.
In spite of its inclusion in the Messier Catalog, this globular cluster was actually discovered by G. Kirch in 1702. According to Recio-Blanco et al.(2005), the distance of M5 is 26,620 light years and its diameter is 150 light years. Its estimated mass is 800,000 solar masses and it contains 143 variable stars.
Messier's Description of M5
May 23, 1764
`Beautiful Nebula discovered between the Balance [Libra] and the Serpent [Serpens], near the star in the Serpent, of 6th magnitude, which is the 5th according to the Catalog of Flamsteed [5 Ser]: it doesn't contain any star; it is round, and one sees it very well, in a fine [clear dark] sky, with an simple refractor of 1 foot. M. Messier has reported it in the chart of the comet of 1763. Mem. Acad for the year 1774, page 40. Reviewed on Sep. 5, 1780, January 30 and March 22, 1781. (Diam. 3')'
- Object: M5
- Other Names: NGC 5904
- Object Type: globular cluster
- Object Data: Apparent Magnitude = 5.6, Angular Size = 17.4 arc-minutes
- Object Position (Equinox 2000): RA= 15h 18.6m, Dec= +02° 05´, Constellation = Serpens
- Date/Time: 2012 Jan 29 at 12:18 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: M5-01w.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.