Some auroral tips available here:
Your magnetic latitude, combined with the intensity of the aurora (measured by the Planetary K index) will give you an idea of whether auroras are likely to be visible from your location.
The following map gives the approximate equatorward boundary for the oval under different conditions:
Australia is quite favourably placed in relation to the south magnetic pole (currently 64.5deg S, 138deg E), almost due south of Adelaide. So our magnetic latitude is higher than our geographic latitude - eg Hobart's magnetic latitude is higher than Edinburgh's, despite being 13deg closer to the equator. Despite this, from Adelaide, you'll still need a planetary K index of >=8 - ie a full geomagnetic storm - in order for the lights to be visible. (They'll be visible a few degrees of latitude north of the oval, but much lower in the southern part of the sky).
If your picture was taken in the early hours of the 4th Jan, it probably wasn't aurora, as the planetary K index was much too low:
The nearest POES passes shows some levels of activity in the early hours of the 4th, but well south of even Tassie:
Very nice picture though!