General fact: 273 is the number of seconds in American composer John Cage's piano composition 4'33" of silence, in three movements.
Mathematical fact: 273 is an unremarkable number.
Trivia: 273 is the death toll of the air crash of American Airlines Flight 191.
Historical date: September 29th is the day in 1982 that the 1982 Chicago Tylenol murders begin when the first of seven individuals dies in metropolitan Chicago.