CREATE TABLE table_44750 ("Date" CLOB, "Series" CLOB, "Circuit" CLOB, "City / State" CLOB, "Winner" CLOB, "Team" CLOB)

What is Circuit, when Series is ASTC Round 4?
SELECT "Circuit" FROM table_44750 WHERE "Series" = 'astc round 4'
SELECT "Circuit" FROM "table_44750" WHERE "Series" = 'astc round 4'