Messier 68 or M68 (also designated NGC 4590) is a globular cluster in the constellation Hydra. It has an apparent visual magnitude of 7.8 and its angular diameter is 12 arc-minutes. M68 lies at an estimated distance of 33,300 light years. The Equinox 2000 coordinates are RA= 12h 39.5m, Dec= -26° 45´ which makes M68 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 M68 through the Takahashi E-180 Astrograph (North is up). The bright star located 1/2 degree southwest of M68 is HR 4803 (magnitude 5.40). A 3x enlargement of this image centered on M68 appears to the right.
This globular cluster was discovered by Messier in 1780. According to Recio-Blanco et al.(2005), the distance of M68 is 36,580 light years and its diameter is 120 light years. It contains 42 variable stars.
Messier's Description of M68
April 9, 1780
`Nebula without stars below Corvus and Hydra; it is very faint, very difficult to see with the refractors; near it is star of sixth magnitude.'
- Object: M68
- Other Names: NGC 4590
- Object Type: globular cluster
- Object Data: Apparent Magnitude = 7.8, Angular Size = 12 arc-minutes
- Object Position (Equinox 2000): RA= 12h 39.5m, Dec= -26° 45´, Constellation = Hydra
- Date/Time: 2011 Apr 04 at 06:13 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: M68-01w.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.