We show that the phase spaces of a large family of line operators in 4d
Chern-Simons theory with $\text{GL}_n$ gauge group are given by Cherkis bow
varieties with $n$ crosses. These line operators are characterized by
Hanany-Witten type brane constructions involving D3, D5, and NS5 branes in an
$\Omega$-background. Linking numbers of the five-branes and mass parameters for
the D3 brane theories determine the phase spaces and in special cases they
correspond to vacuum moduli spaces of 3d $\mathcal{N}=4$ quiver theories.
Examples include line operators that conjecturally create T, Q, and L-operators
in integrable spin chains.
