Timezone template for to_char(timestamp, '...')?

I'm using

    to_char(timestamp, 'Dy @MM:MIAM, Mon DD, YYYY')

to format a timestamp and its works fine except I'd like to add the timezone
(EDT etc) to the end.

Is there a format template for timezone?  I thought TZ might be it, but it
doesn't work.

The documentation for to_char() is here:
http://www.postgresql.org/docs/postgres/x2976.htm

--
Robert B. Easter