The hitherto unknown 8mm colour film of JFK's last motorcade, donated to the Sixth Floor Museum in Dallas, does not cover the assassination itself. Instead its centrepiece is a radiant Jacqueline Kennedy, waving to the crowds lining the downtown pavement, a few blocks from Dealey Plaza where her husband John was assasinated.

The sky is cloudless, Dallas' skyscrapers are bedecked with the national flag, and excited bystanders wave at the camera as they wait for the Kennedys. Most poignant of all however is the image of the First Lady: "The clearest, best film of Jackie in the motorcade," says Gary Mark, curator of the museum which released the 39-second film on its website to coincide with Monday's Presidents Day holiday in the US.

This being the Kennedy assassination however, even these apparently innocuous pictures will be scrutinised by conspiracy theorists. The film clearly shows the President sitting beyond Jackie, his suit jacket bunched up on his back - which may bear upon claims that disparities in the bullet marks on his jacket and body prove Lee Harvey Oswald could not have been the only gunman.