The predicted nature of the candidate redback pulsar 4FGL J2039.5 - 5617 was recently confirmed by the discovery of \gamma -ray millisecond pulsations ( Clark et al .
2020 , hereafter Paper I ) , which identify this \gamma -ray source as PSR J2039 - 5617 .
We observed 4FGL J2039.5 - 5617 with the Parkes radio telescope in 2016 and 2019 .
We detect radio pulsations at 1.4 GHz and 3.1 GHz , at the 2.6 ms period discovered in \gamma -rays , and also at 0.7 GHz in one 2015 archival observation .
In all bands , the radio pulse profile is characterised by a single relatively broad peak which leads the main \gamma -ray peak .
At 1.4 GHz we found clear evidence of eclipses of the radio signal for about half of the orbit , a characteristic phenomenon in redback systems , which we associate with the presence of intra-binary gas .
From the dispersion measure DM = 24.57 \pm 0.03 pc cm ^ { -3 } we derive a pulsar distance of 0.9 \pm 0.2 kpc or 1.7 \pm 0.7 kpc , depending on the assumed Galactic electron density model .
Both the 1.4 GHz Parkes observations obtained in 2016 and 2019 and Swift monitoring campaign ( 2017–2018 ) show no obvious long-term changes in the pulsar radio and X-ray emission .
The modelling of the radio and \gamma -ray light curves leads to an independent determination of the orbital inclination , and to a determination of the pulsar mass , qualitatively consistent to the results in Paper I .