Best guess is Cosmos 1383, assuming you clock is accurate and you really are in central Melbourne.
Calsky is the tool you want to use.
Appears 20h31m59s 9.7mag az:348.8° N horizon
Closest 20h39m58s 6.9mag separation: 1.3° PA: 95.3°
Culmination 20h40m35s 6.8mag az:262.2°
W h:71.3°
distance: 1020.7km height above Earth: 974.2km elevation of Sun: -31° angular velocity: 0.42°/s
at Meridian 20h45m27s 8.9mag az:180.0° S h:17.7°
Disappears 20h49m24s 10.1mag az:175.1° S horizon