[1] CAE Elect Ltee, St Laurent, PQ H4L 4X4, Canada
[2] Univ Montreal, Dept Phys, Montreal, PQ H3C 3J7, Canada
[3] Lockheed Martin Canada, Montreal, PQ H4P 1K6, Canada
[4] Villanova Univ, Dept Astron & Astrophys, Villanova, PA 19085 USA
[5] Univ Arizona, Steward Observ, Tucson, AZ 85721 USA