Using current time in UTC as default value in PostgreSQL
A function is not even needed. Just put parentheses around the default expression:
create temporary table test( id int, ts timestamp without time zone default (now() at time zone 'utc'));
Wrap it in a function:
create function now_utc() returns timestamp as $$ select now() at time zone 'utc';$$ language sql;create temporary table test( id int, ts timestamp without time zone default now_utc());