The system records the date-time of the operation causing a trigger to fire. If the trigger causes the execution of a workflow this date-time is passed in the 'action_Time' parameter. If the trigger causes alerts to be sent to client the time is included in the alert packet.

The operation date-time is the same that is recorded in the audit-trail (within the precision of the date-time columns in the database being used - 3.33 milliseconds for SQL Server)