We present the first resolved imaging of the milliarcsecond-scale jets in the neutron star X-ray binary Circinus X-1 , made using the Australian Long Baseline Array .
The angular extent of the resolved jets is \sim 20 milliarcseconds , corresponding to a physical scale of \sim 150 au at the assumed distance of 7.8 kpc .
The jet position angle is relatively consistent with previous arcsecond-scale imaging with the Australia Telescope Compact Array .
The radio emission is symmetric about the peak , and is unresolved along the minor axis , constraining the opening angle to be < 20 ^ { \circ } .
We observe evidence for outward motion of the components between the two halves of the observation .
Constraints on the proper motion of the radio-emitting components suggest that they are only mildly relativistic , although we can not definitively rule out the presence of the unseen , ultra-relativistic ( \Gamma > 15 ) flow previously inferred to exist in this system .