  In this paper we re-examine historical references to the supernova event of
1054 AD with a view to establishing a sequence astronomical events which
minimizes apparent conflicts between the various sources. We find that the
explosion of the supernova is likely to have occurred weeks to months before
the commonly accepted date of July 4th 1054. This view is strongly supported by
a number of European references to events visible in the evening sky during the
spring which are likely to be associated with the appearance of the supernova.
We find the best fit to the light curve based on Chinese observations and a
maximum visible apparent magnitude for a supernova located at the distance to
the Crab Nebula also confirms the earlier explosion date.
