Messier 19 — Globular Cluster in Ophiuchus
NGC 6273
About M19
Description
M19 is a globular cluster in the constellation Ophiuchus, located about 28,700 light-years from Earth. It is one of the most oblate (flattened) globular clusters known, with a noticeably elliptical appearance. M19 contains several hundred thousand stars and spans about 140 light-years in diameter. It lies only about 6,500 light-years from the galactic center, making it one of the innermost Milky Way globular clusters. Its proximity to the galactic center likely causes the tidal forces responsible for its elongated shape.
Observing Tips
Located about 8 degrees south-southeast of Antares. At magnitude 7.5, it is visible in binoculars as a small fuzzy spot. A 4-inch telescope shows a round to slightly oval glow with a brighter center. The elliptical shape becomes more apparent in 8-inch or larger telescopes at 150x or more. Star resolution is difficult due to its distance and compact nature — apertures of 10 inches or more are needed to resolve the outer fringes. Best observed from June through August.
History
Discovered by Charles Messier on June 5, 1764. He described it as a round nebula without stars. William Herschel was the first to note its slightly elliptical shape. The cluster's unusual oblateness has been studied extensively, with modern research attributing it to tidal forces from the galactic center.
Fun Facts
M19 is the most oblate globular cluster in the Messier catalog, with an ellipticity of about 0.22. Its flattened shape is thought to be caused by the strong tidal field near the galactic center. The cluster is one of the closest known globular clusters to the center of the Milky Way, orbiting in a region of intense gravitational forces.
Observe
1Properties
Position & Identifiers
2How easy to spot?
| Telescope | Bortle 3 | Bortle 4 | Bortle 5 |
|---|---|---|---|
| 80 mm refractor 80mm refr. | Easy | Easy | Easy |
| 150 mm Newton 150mm Newt. | Easy | Easy | Easy |
| Celestron C8 (203 mm SCT) C8 203mm | Easy | Easy | Easy |
Bortle 3 = rural · 4 = outer suburbs · 5 = suburbs
3Visibility
Set a location in User Settings to see visibility data.
4
Eyepiece View
5
Best Magnification
6Metallicity
[Fe/H] = -1.74 — these stars formed from gas about 55× poorer in iron than the Sun.
7Concentration class
Shapley-Sawyer class IV — moderately concentrated core.
Explore
8
Classification Decoder
Discover
9
Light Travel Time Machine
10
Relativistic Travel
Community Photos (1)
Credit: Doug Williams, REU Program / NOIRLAB / NSF / AURA. License: CC BY-SA 4.0. (Wikimedia Commons)
Skybred Feb 28, 2026
Nearby in the Sky
Other targets within a few degrees — pan your scope a little and keep exploring.
Visibility scores assume a 150 mm Newton at Bortle 4.
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