The SYSTIMESTAMP function returns the current date and time as a
    TIMESTAMP type. This function is similar to SYSDATE and CURRENT_
    TIMESTAMP however, its type doesn't change when the SET DEFAULT
    DATE FORMAT command is used.

    Syntax: SYSTIMESTAMP [ ( fractional-seconds-precision ) ]

    The function name can be followed by an optional fractional-
    seconds-precision. This value, if omitted, defaults to 2 and
    accepts the values 0, 1, or 2.

    The following example shows that SYSTIMESTAMP always returns a
    SQL standard date and time.

    SQL> select systimestamp,sysdate,current_timestamp from rdb$database;
     2007-03-27 16:33:32.19   27-MAR-2007 16:33:32.19   27-MAR-2007 16:33:32.19
    1 row selected
    SQL> set default date format 'sql99';
    SQL> select systimestamp,sysdate,current_timestamp from rdb$database;

     2007-03-27 16:33:41.32   2007-03-27 16:33:41.32   2007-03-27 16:33:41.32
    1 row selected
    SQL>