  As part of our massive spectroscopic survey of 25 Galactic globular clusters
with MUSE, we performed multiple epoch observations of NGC 3201 with the aim of
constraining the binary fraction. In this cluster, we found one curious star at
the main-sequence turn-off with radial velocity variations of the order of 100
km/s, indicating the membership to a binary system with an unseen component
since no other variations appear in the spectra. Using an adapted variant of
the generalized Lomb-Scargle periodogram, we could calculate the orbital
parameters and found the companion to be a detached stellar-mass black hole
with a minimum mass of 4.36 $\pm$ 0.41 solar masses. The result is an important
constraint for binary and black hole evolution models in globular clusters as
well as in the context of gravitational wave sources.
