[1] HARVARD UNIV,SMITHSONIAN CTR ASTROPHYS,CAMBRIDGE,MA 02138
[2] NASA,AMES RES CTR,MOFFETT FIELD,CA 94035
[3] CALTECH,DIV GEOL & PLANETARY SCI,PASADENA,CA 91125
[4] UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,LONDON WC1E 6BT,ENGLAND
[5] UNIV HAWAII,INST ASTRON,HONOLULU,HI 96822
[6] SUNY STONY BROOK,STONY BROOK,NY 11790
[7] UNIV ARIZONA,DEPT PLANETARY SCI,TUCSON,AZ 85721