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Messier 6 (M6) or NGC 6405 is a mature open cluster (age: about 100 Million years old). Usually, this kind of clusters contains only massive, hot, young blue stars, but M6’s brightest star is BM Sco, an orange K-type giant. This cluster is located in the constellation Scorpius at a distance of 1,585 light years. The orbit of this cluster around the galactic center was determined in 2009 by Wu et al. Its orbit is pretty much circular (eccentricity 0.03) and lasts for 204.2 Million years. As many as 120 stars (magnitude 15.1 and above) have been identified to belong to this cluster.
Additional Information
Object
Name(s): Messier 6. NGC 6405. Butterfly Cluster
Type: Open Cluster
RA: 17h 40m 19s
Dec: -32º 14’ 54”
Constellation: Scorpius
Size (arcmin): 25 arcmin
Magnitude: +4.2
Distance: 1,595 ly
Image
Date: 2020-05-27 to 2020-07-24
Location: iTelescope.net, SSO near Coonabarabran, NSW Australia
Size (arcmin): 37×37 arcmin
Telescope: 20” f/6.8 Reflector
Camera: SBIG STX16803 (4096x4096pix)
Guiding: Astrodon MonsterMOAG off-axis guider
Total exposure: 5 hours (L: 2 hours; RGB: 3 hours)
Processing: CCDStack, Photoshop CC 2020