I like the hypothesis that it represents a shiplog entry rather than a form of interstellar calender, not that it's a valid hypothesis.... Gene originally used it as a way to avoid mentioning what year Star Trek takes place in. It wasn't until much later that someone tried to use it as an actual calender.
Use this calculator, it uses the same conversion as in game. Basically the in game year is 400 years ahead of the date you enter and it is then converted to stardate format. So for 2409, enter a date in 2009.
Wouldn't it be awesome if we could do a tag [Stardate] and it would be replaced with the current stardate, so it changes with time. Also [Stardate-xyz] for xyz ago or [Stardate+xyz] for xyz in the future.
Interesting stuff. Star Treks idea of time and dates being constant across the galaxy flies in the face of Einstien's general relativity though. A person in a jet aircraft is experiencing time differently than you and i are on the ground.
Play more STO Foundry! (You can thank me later.)
A TIME TO SEARCH: ENTER MY FOUNDRY MISSION at the RISA SYSTEM in the SIRIUS SECTOR
According to ingame log, my last entry log if from stardate 90758.19
You may want to use the Ingame stardate, even if the stardate is probably running since the release, which was 3years ago (which mean it's the year 2412, according to this stardate, while still being 2409 officially).
You can see the stardate in you log. Select the entry you want to see, and there are both stardate and earth date. Earth date being "our time" date.
The stardates in the log are based on when the individual character started, not the game. So the stardates are different for every character. A character that was started during headstart, will have a significantly higher stardate than one only started two weeks ago.