PL/SQL :: Get DAY Based On Current / Given Territory From Number Between 1 And 7?

Looks like I am at the end of my wits here but how to get the "DAY" based on current/given territory from a number between 1 and 7? Oracle has functions to extract day of the week but I can't find the other way round.

SQL> select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production

SQL> alter session set nls_territory=AMERICA;

Session altered.

SQL> select to_char (sysdate, 'D') from dual;

T
-
3

SQL> alter session set nls_territory=GERMANY;

Session altered.

SQL> select to_char (sysdate, 'D') from dual;

T
-
2

I need a way to know that number "3" on database with NLS_TERRITORY = AMERICA means a "Tuesday" or number "2" on a database with NLS_TERRITORY=GERMANY means "Tuesday" as well.