A stardate was a unit of time measurement in use in the United Federation of Planets.
On Stardate 3368.5, in the year 2267, the USS Enterprise commanded by Captain James T. Kirk visited the planet Aprilia III, where they fought the Cybermen with assistance from the Fourth Doctor.
On Stardate 45635.2, in the year 2368, the Federation planet of Delta IV was invaded by an alliance of Cybermen and the Borg. (COMIC: Assimilation²)
Behind the scenes[]
The usage of stardates in Assimilation² places the events securely between episodes of Star Trek: The Original Series and Star Trek: The Next Generation.
James T. Kirk's encounter with the Fourth Doctor takes place between The Original Series episodes Operation -- Annihilate!, the finale of season 1, and Amok Time, the premiere of season 2.
Jean-Luc Picard's encounter with the Eleventh Doctor takes place within the fifth season of The Next Generation, between the episodes The Outcast and Cause and Effect.