For future reference, the JPL small body database entry on the comet:

http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=C%2F2013%20A1;orb=1;cov=0;log=0;cad=1;rad=0#cad

Different sources seem to have different orbital calculations, this one indicates a most likely close approach of ~100,000 kilometers with the uncertainty wide enough to include a close approach of 0 km.

If nothing else, we very well may get pictures from the surface rovers of the head of a comet literally filling the sky.