[5] The first astronomer to record the Butterfly Cluster's existence was Giovanni Battista Hodierna in 1654.

[8] Wu et al. (2009) found a distance estimate of 1,590 light-years,[1] giving it a spatial dimension of some 12 light years.

[3] Modern measurements show its total visual brightness to be magnitude 4.2.

Cluster members show a slightly higher abundance of elements heavier than helium compared to the Sun;[9] what astronomers refer to as the metallicity.

120 stars, ranging down to visual magnitude 15.1, have been identified as most likely cluster members.