M 6 (NGC 6405)
Open Star Cluster in Scorpius
| Common Names: | Butterfly Cluster |
| Position (J2000): | 17h40m06s -32°13'00" |
| Magnitude: | 4.2 |
| Size: | 33' |
| Class: | II 3 r |
| Finder Charts: | 30° | 15° | 5° |
| Search Radius: | 5° |
| NGC Description: | Cl, L, iR, lC, st 7, 10...; = M6 |
| Other Identifiers: | Cr 341, Mel 178, Lund 769, ESO 455-SC030, h 3699, GC 4318 |
M6 is visible to the naked eye in the constellation Scorpius. The visually most conspicuous star is rather reddish and is actually a slow, semiregular variable.
M6 was recognized as a cluster by Hodierna prior to 1654 but was recognized by Ptolemy along with M7 in the 2nd century B.C. as two "small clouds" near the sting of the scorpion. M6 is 1500 light years distant with a luminosity of 8300 suns. M6 is also known as "The Butterfly Cluster" because of its distinctive "pinch" in the middle. In the eyepiece it is best viewed at low power, and at 50x it shows many members with a bright orange star off the ENE edge. The best view of this cluster is with a pair of binoculars.
Learn more about M 6 on the web, browse the observing lists containing M 6, or review the references used to gather information regarding M 6. Read observations made by other observers such as Charles Messier.
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Images
Observations
| ID | Description |
|---|---|
| 2017 | Indiana Family Star Party 2008 - August 2, 2008 03:34 UT At 142x with the 13mm eyepiece in the 368mm reflector, M 6 appears as a large, loosely scattered collection of blue stars of nearly the same magnitude. The cluster fills the eyepiece field of view. A conspicuous arrow shape of six fainter stars points toward the center of the cluster. |
| 1681 | Scoping out a new observing site - July 14, 2007 04:00 UT At 77x with the 24mm eyepiece in the 368mm reflector, M 6 appears as a dense cluster of stars that fills two-thirds of the eyepiece field of view. The stars within the cluster have a small difference in magnitude. With averted vision, the central region of the cluster is resolved into faint background stars. The estimated Trumpler class is II 2 r. |
| 1667 | A tour of the Milky Way with binoculars - July 7, 2007 02:51 UT In 12x60 binoculars, M6 appears as a loose, poorly defined cluster of approximately twelve stars. With averted vision, fainter stars are resolved in the background of the cluster, which continues to exhibit a very faint nebulous glow in the background. This glow may be even fainter stars that are not resolved. |
| 1121 | Summer nights public program - July 27, 2003 04:10 UT At 52x with the 24mm eyepiece in the 90mm Maksutov, M6 appears as a large, loose, and poorly defined open cluster of approximately thirty bright stars. Averted vision does not reveal any fainter stars in the background. The outline of a butterfly is easily detectable lying in an east-west direction. |
| 469 | Double vision gets the best of me - May 5, 2002 07:19 UT With the 203mm SCT at 92x in the 22mm eyepiece, M6 fills the majority of the 44’ field of view. M6 is a large, loose open cluster of mostly blue/white stars. Averted vision did not reveal any fainter members buried within the brighter members of the cluster. An arrangement of stars resembling the wings and antennae of a butterfly was very evident near the center of the cluster. |
| 23 | Binocular bonanza - May 15, 2001 06:20 UT Both M6 and M7 appear within the same 8° field of view in the 7x35 binoculars. M6 appears as an oval smudge with six to ten scattered stars. In 10x50 binoculars, M7 still appears with M6 in the 6.5° field of view. M6 appears more resolved than with the 7x35 binoculars with dozens of stars visible and just a hint of nebulosity. In 20x70 binoculars, M6 is completely resolved into individual stars. The brighter stars form an inverted chevron pattern through the center of the cluster. |
