Public index · Astronomy
Aculeus
mag 4.20
Measured
Open cluster Messier 6 (Aculeus), combined visual magnitude
M6, the Butterfly, is catalogued near magnitude 4.2. How we see. A cluster, not a star. NASA SkyView DSS of NGC 6405. Door to Scheat.
What it supports
A cluster brightness, not a star. Family is 4.20, not 42. How we see: the eye’s threshold is the point.
What it does not
Not 42°. Not natal proof. Magnitude tables round; 4.2 and 4.20 are the same wink.
ExactnessApproximate
Form4.2
Unitmag
Strengthattested