You might be thinking that every day is Star Trek Day in STO, but the 8th of September is the official date which will last until September 22nd.
From September 8th at 8am PT (17:00 CEST) til September 22nd at 10am PT 19:00 CEST), on all platforms, there will be a special Starfleet Museum in orbit above Deep Space Nine and Earth Space Dock. The museum contains the starring ships from Star Trek movies, television, and more. Hailing each ship will give you words from their crew, and both in universe and behind the scenes facts about the ship and show. Hailing all ten of the ships will grant you a special title: Historical Documents Expert.