A SN can become brighter than an entire galaxy for a short time. The reason they do so is different from the Type Ia case above. Massive stars can burn elements up to Fe. However, the iron does not release energy when undergoing fusion, so it doesn't burn. Burning stops in the core, and the core begins to contract.
Fusion occurs in a shell around the iron core, so the iron core continues building in mass.
At this stage, contraction is resisted and a violent 'shudder' moves through the gas layers. The Chinese recorded SN in 1006 and 1054. The latter is associated with what is now called the Crab nebula. This cloud of gas is the remnant from the SN explosion. Brahe recorded a SN in 1572 and Kepler observed one in 1604.