user: Question: What is Circuit, when Series is ASTC Round 4?
Columns: ['Date', 'Series', 'Circuit', 'City / State', 'Winner', 'Team']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['5 - 7 Mar', 'Hot Wheels V8 Supercar Showdown', 'Albert Park street circuit', 'Melbourne , Victoria', 'Craig Lowndes', 'Holden Racing Team']
SQL:

assistant: SELECT "Circuit" FROM "Table" WHERE "Series" = 'ASTC Round 4';