M54
Messier 54 or M54 (also designated NGC 6715) is a globular cluster in the constellation Sagittarius. It has an apparent visual magnitude of 7.6 and its angular diameter is 9.1 arc-minutes. M54 lies at an estimated distance of 88,700 light years. The Equinox 2000 coordinates are RA= 18h 55.1m, Dec= -30° 29´ which makes M54 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 M54 through the Takahashi E-180 Astrograph (North is to right). A 3x enlargement of this image appears to the right.
This globular cluster was discovered by Messier in 1778. In 1994, it was discovered that M54 is not a member of the Milky Way but belongs to a newly identified dwarf galaxy known as SagDEG (Sagittarius Dwarf Elliptical Galaxy). According to Recio-Blanco et al.(2005), the distance of M54 is 84,650 light years and its diameter is 300 light years. Its estimated mass is 1.5 million solar masses and it contains 211 variable stars.
For more information, see the Messier Catalog as well as specific entries for M54 in Wikipedia and SEDS.
Messier's Description of M54
July 24, 1778
`Very faint nebula, discovered in Sagittarius; its center is brilliant and it contains no star, seen with an achromatic telescope of 3.5 feet. Its position has been determined from Zeta Sagittarii, of 3rd magnitude.'
Technical Details
- Object: M54
- Other Names: NGC 6715
- Object Type: globular cluster
- Object Data: Apparent Magnitude = 7.6, Angular Size = 9.1 arc-minutes
- Object Position (Equinox 2000): RA= 18h 55.1m, Dec= -30° 29´, Constellation = Sagittarius
- Date/Time: 2011 Oct 20 at 02:28 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: 6 x 300s, f/2.8, ISO 800
- File Name: M54-01w.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.