Messier 80 or M80 (also designated NGC 6093) is a globular cluster in the constellation Scorpius. It has an apparent visual magnitude of 7.3 and its angular diameter is 8.9 arc-minutes. M80 lies at an estimated distance of 32,600 light years. The Equinox 2000 coordinates are RA= 16h 17m, Dec= -22° 59´ which makes M80 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 M80 through the Takahashi E-180 Astrograph (North is up). A 3x enlargement of this image appears to the right.
This globular cluster was discovered by Messier in 1781. It is one of the densest globulars in the Milky Way Galaxy and contains several hundred thousand stars. According to Recio-Blanco et al.(2005), the distance of M80 is 48,260 light years and its diameter is 125 light years. Its estimated mass is 400,000 solar masses and it contains 10 variable stars.
Messier's Description of M80
January 4, 1781
`Nebula without star, in Scorpius, between the stars g. [now Rho Ophiuchi] and Delta, compared to g to determine its position: this nebula is round, the center brilliant, and it resembles the nucleus of a small Comet, surrounded with nebulosity. M. Méchain saw it on January 27, 1781.' (diam. 2')
- Object: M80
- Other Names: NGC 6093
- Object Type: globular cluster
- Object Data: Apparent Magnitude = 7.3, Angular Size = 8.9 arc-minutes
- Object Position (Equinox 2000): RA= 16h 17m, Dec= -22° 59´, Constellation = Scorpius
- Date/Time: 2011 Apr 11 at 10:17 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: 2 x 300s, f/2.8, ISO 800
- File Name: M80-01w.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.