  Recent observations by Mauerhan et al. have shown the unprecedented
transition of the previously identified luminous blue variable (and supernova
impostor) SN 2009ip to a real Type IIn supernova (SN) explosion. We present
high-cadence optical imaging of SN 2009ip obtained between 2012 UT Sep. 23.6
and Oct. 9.6, using 0.3-0.4 meter aperture telescopes from the Coral Towers
Observatory in Cairns, Australia. The light curves show well-defined phases,
including very rapid brightening early on (0.5 mag in 6 hr observed during the
night of Sep. 24), a transition to a much slower rise between Sep. 25 and Sep.
28, and a plateau/peak around Oct. 7. These changes are coincident with the
reported spectroscopic changes that, most likely, mark the start of a strong
interaction between the fast SN ejecta and a dense circumstellar medium formed
during the earlier LBV eruptions. In the 16-day observing period SN 2009ip
brightened by 3.7 mag from I = 17.4 mag on Sep. 23.6 (MI = -14.2) to I = 13.7
mag (MI = -17.9) on Oct. 9.6, radiating ~2x10^49 erg in the optical wavelength
range. Currently, SN 2009ip is more luminous than most Type IIP SNe and
comparable to other Type IIn SNe.
