Thüringer Landessternwarte Tautenburg
19139 Apian, provisional designation "", is a bright background asteroid from the central regions of the asteroid belt, approximately 6 kilometers in diameter. It was discovered on 6 April 1989, by German astronomer Freimut Börngen at the Karl Schwarzschild Observatory in Tautenburg, Eastern Germany. The asteroid was named for medieval German humanist Petrus Apianus.