1759 Kienle, provisional designation 1942 RF, is a stony background asteroid from the central regions of the asteroid belt, approximately 7 kilometers (4.3 miles) in diameter. It was discovered on 11 September 1942, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany. The S-type asteroid has a longer-than average rotation period of 29.3 hours. It was named for German astrophysicist Hans Kienle.