  The radio:X-ray correlation that characterises accreting black holes at all
mass scales - from stellar mass black holes in binary systems to super-massive
black holes powering Active Galactic Nuclei - is one of the most important
pieces of observational evidence supporting the existence of a connection
between the accretion process and the generation of collimated outflows - or
jets - in accreting systems. Although recent studies suggest that the
correlation extends down to low luminosities, only a handful of stellar mass
black holes have been clearly detected, and in general only upper limits
(especially at radio wavelengths) can be obtained during quiescence. We
recently obtained detections of the black hole X-ray binary GX 339--4 in
quiescence using the MeerKAT radio telescope and Swift X-ray Telescope
instrument onboard the Neil Gehrels Swift Observatory, probing the lower end of
the radio:X-ray correlation. We present the properties of accretion and of the
connected generation of jets in the poorly studied low-accretion rate regime
for this canonical black hole XRB system.
