Messier 19 or M19 (also designated NGC 6273) is a globular cluster in the constellation Ophiuchus. It has an apparent visual magnitude of 6.8 and its angular diameter is 13.5 arc-minutes. M19 lies at an estimated distance of 28,400 light years. The Equinox 2000 coordinates are RA= 17h 02.6m, Dec= -26° 16´ which makes M19 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 M19 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 1764 but he was unable to resolve it into stars. M19 is one of the most oblate globular clusters known. The deformation of its shape may be due to its proximity (5200 light years) to the Galactic Center. According to Recio-Blanco et al.(2005), the distance of M19 is 45,000 light years and its diameter is 180 light years. Its estimated mass is 1.5 million solar masses and it contains 8 variable stars.
Messier's Description of M19
June 5, 1764
`Nebula without stars, on the parallel of Antares between Scorpius and the right foot of Ophiuchus: this nebula is round; one can see it very well with an simple refractor of 3.5 feet; the nearest neighboring known star to this nebula is 28 Ophiuchi, which is of mag. 6, according to Flamsteed.' (diam. 3')
- Object: M19
- Other Names: NGC 6273
- Object Type: globular cluster
- Object Data: Apparent Magnitude = 6.8, Angular Size = 13.5 arc-minutes
- Object Position (Equinox 2000): RA= 17h 02.6m, Dec= -26° 16´, Constellation = Ophiuchus
- Date/Time: 2011 Apr 12 at 10:28 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: 2 x 300s, f/2.8, ISO 800
- File Name: M19-01w.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.