Flashbacks based on system change numbers (SCNs) can be more precise than those based on a time, because the database uses SCNs to track changes.
SQL> VARIABLE current_scn NUMBER
SQL> EXECUTE :current_scn := DBMS_FLASHBACK.GET_SYSTEM_CHANGE_NUMBER();
PL/SQL procedure successfully completed.
SQL> PRINT current_scn
CURRENT_SCN
-----------
5547739
SQL>