Messier 39 or M39 (also designated NGC 7092) is an open cluster in the constellation Cygnus. It has an apparent visual magnitude of 4.6 and its angular diameter is 32 arc-minutes. M39 lies at an estimated distance of 825 light years. The Equinox 2000 coordinates are RA= 21h 32.2m, Dec= +48° 26´ which makes M39 best seen during the autumn. The Messier Autumn Star Chart shows the position of all Messier objects visible during that season.
The image above shows the uncropped view of M39 through the Takahashi E-180 Astrograph (North is to right). A 2x enlargement of this image appears to the right.
This loose open cluster was discovered by Messier in 1764. According to Kharchenko et al. (2005), the distance of M39 is 1010 light years and its diameter is 9 light years. It contains 60 stars and its estimated age is 240-480 million years.
Messier's Description of M39
October 24, 1764
`Cluster of stars near the tail of the Swan; one can see them with an simple refractor of 3.5 feet.' (diam. 1d 00')
- Object: M39
- Other Names: NGC 7092
- Object Type: open cluster
- Object Data: Apparent Magnitude = 4.6, Angular Size = 32 arc-minutes
- Object Position (Equinox 2000): RA= 21h 32.2m, Dec= +48° 26´, Constellation = Cygnus
- Date/Time: 2011 Oct 20 at 04:15 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: M39-01w.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.