CREATE TABLE table_8653 ("Event" TEXT, "PDT  ( -7 UTC ) " TEXT, "MDT  ( -6 UTC ) " TEXT, "CDT  ( -5 UTC ) " TEXT, "EDT  ( -4 UTC ) " TEXT)

What is the time for PDT when CDT is 6:38 a.m.?
SELECT "PDT (-7 UTC)" FROM table_8653 WHERE "CDT (-5 UTC)" = '6:38 a.m.'
SELECT "PDT (-7 UTC)" FROM "table_8653" WHERE "CDT (-5 UTC)" = '6:38 a.m.'