[1] UNIV LONDON UNIV COLL,DEPT PHYS & ASTRON,LONDON WC1E 6BT,ENGLAND
[2] RUTHERFORD & APPLETON LABS,ASTROPHYS GRP,DICOT OX11 OQX,OXFORDSHIRE,ENGLAND
[3] STOCKHOLM OBSERV,SALTSJOBADEN,SWEDEN
[4] EUROPEAN SO OBSERV,GARCHING,FED REP GER
[5] UNIV OXFORD,DEPT THEORET PHYS,OXFORD,ENGLAND
[6] LUND OBSERV,LUND,SWEDEN
[7] UNIV MILAN,IST FIS,I-20133 MILAN,ITALY
[8] CNR,IST FIS COSMICA,I-20133 MILAN,ITALY
[9] ROYAL GREENWICH OBSERV,HAILSHAM BN27 1RP,SUSSEX,ENGLAND