What is the circuit on 19 Apr with Craig Lowndes as the winner?
CREATE TABLE "race_calendar" (
  "date" text,
  "series" text,
  "circuit" text,
  "city_state" text,
  "winner" text,
  "team" text
);
SELECT "circuit" FROM "race_calendar" WHERE "winner"='craig lowndes' AND "date"='19 apr';