The exponential drop in the brightness of supernova 1987A was due to the decay of 56Ni (...

The exponential drop in the brightness of supernova 1987A was due to the decay of ⁵⁶Ni (t^1/2 = 6.1 days) ⁵⁶Co (t^1/2 = 77.1 days) ⁵⁶Fe. If the energy were primarily due to the decay of 56Ni, what falloff in brightness by the end of 300 days would we expect? What if it were due to the energy in the decay of ⁵⁶Co? The actual data showed a decrease in brightness by a factor of about 100 after 300 days.