70 light-years across. (Warp 6 crossing would take two months from side to side.)
Home to two navigation grade Pulsar’s, one of which is CX-1 a pulsar/neutron star binary. (CX-1 is possibly a Prior artefact)
A higher number of habitable M-class worlds than should be possible in a star cluster of this size.
Messier 4 is 8500 light years from Sol, orbiting above the plain of the ecliptic of the Milky Way, straddling the divide between the Sagittarius and Centaurus arms of the galaxy.