[1] Univ Cent Lancashire, Jeremiah Horrocks Inst, Preston, Lancs, England
[2] Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA
[3] Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA
[4] Tokushima Univ, Inst Liberal Arts & Sci, Tokushima, Japan
[5] Kagoshima Univ, Dept Phys & Astron, Fac Sci, Kagoshima, Japan