This might be too obvious, but I think that there ought to be some indication of whether the event of a specific date is to be celebrated or mourned.
Clearly, the burning down of Charles K. Johnson's house was an unmitigated disaster and tragedy and shouldn't be observed in the same manner as the bestowal of Rowbotham's degree.
Would a smiley suffice?
I like this idea. I propose

for births,

for other significant positive events in the history of the FES,

for deaths and catastrophic events in the FES's history, and either

or

for events dealing with NASA and the Conspiracy, depending on whether we want to convey our anger over their existence or their own cheekiness.