  The IceCube neutrino telescope monitors one cubic kilometer of deep Antarctic
ice by detecting Cherenkov photons emitted from charged secondaries produced
when neutrinos interact in the ice. The geometry of the detector, which
comprises a lattice of 5160 photomultipliers, is optimized for the detection of
neutrinos above 100 GeV. However, at subfreezing ice temperatures, dark noise
rates are low enough that a high flux of MeV neutrinos streaming through the
detector may be recognized by a collective rate enhancement in all
photomultipliers. This method can be used to search for the signal of core
collapse supernovae, providing sensitivity competitive to Mton neutrino
detectors to a supernova in our Galaxy. An online data acquisition system
dedicated to supernova detection has been running for several years, but its
shortcomings include limited sampling frequency and the fact that the burst
energy and direction cannot be reconstructed. A recently developed offline data
acquisition system allows IceCube to buffer all registered photons in the
detector in case of an alert with low probability to be erroneous. By analyzing
such data offline, a precision determination of the burst onset time and the
characteristics of rapidly varying fluxes, as well as estimates of the average
neutrino energies may be obtained. For supernovae ending in a black hole, the
IceCube data can also be used to determine the direction of the burst.
