MS#38. A Chaotic Blue Sky Catastrophe in Forced Relaxation Oscillations, 1985 with H. Bruce Stewart Physica 21D, 1986, pp. 394-400. Abstract: The chaotic attractor of a periodically forced Van der Pol oscillator (Shaw variant) is observed in digital simulation, and is made to vanish in a blue sky catastrophe by increasing a constant (bias) term in the force. The detailed bifurcation diagram, based on extensive simulations, reveals the involvement of the homoclinic outset of a nearby limit cycle of saddle type. [PDF] 7 pages, 700 KB Last revised by Ralph Abraham