SELECT SYSTIMESTAMP,
       DBTIMEZONE,
       CURRENT_TIMESTAMP
       SESSIONTIMEZONE
  FROM DUAL;

=============================================================================================================================================================================================================
|                   SYSTIMESTAMP                   |                    DBTIMEZONE                    |                CURRENT_TIMESTAMP                 |                 SESSIONTIMEZONE                  |
=============================================================================================================================================================================================================
|            20.07.2017 7:15:33 -04:00             |                  Europe/Moscow                   |            20.07.2017 14:15:33 +03:00            |                      +03:00                      |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

SELECT
  SYSTIMESTAMP,
  SYSTIMESTAMP AT TIME ZONE 'Europe/Moscow' Moscow,
  SYSTIMESTAMP AT TIME ZONE 'America/New_York' New_York
  FROM DUAL

==========================================================================================================================================================
|                   SYSTIMESTAMP                   |                      MOSCOW                      |                     NEW_YORK                     |
==========================================================================================================================================================
|            20.07.2017 7:09:25 -04:00             |            20.07.2017 11:09:25 +00:00            |            20.07.2017 11:09:25 +00:00            |
----------------------------------------------------------------------------------------------------------------------------------------------------------