Over what time period is 'Today' measured for the Game Center leaderboard?

Does anyone know over what time period the Game Center leaderboards measure 'Today'? In other words, if I play a game and get a high score for 'Today开发者_如何转开发', at what time does that score no longer appear in the 'Today' category?

12:00 AM PTZ <== that's where apple is

"Today" in Apple's Game Center really means the most relevant score in the past 24 hours (even though this can easily span more than one actual day).

Here's a reference to the time scope documentation for GKLeaderboardTimeScopeToday:

Each player is restricted to scores recorded in the past 24 hours.

http://developer.apple.com/library/ios/#DOCUMENTATION/GameKit/Reference/GKLeaderboard_Ref/Reference/Reference.html#//apple_ref/c/econst/GKLeaderboardTimeScopeToday