[1] LUND OBSERV, S-22100 LUND, SWEDEN
[2] ROYAL GREENWICH OBSERV, CAMBRIDGE CB3 0EZ, ENGLAND
[3] EUROPEAN SPACE AGCY, ESTEC, DIV ASTROPHYS, 2200 AG NOORDWIJK, NETHERLANDS
[4] COPENHAGEN UNIV OBSERV, DK-1350 COPENHAGEN K, DENMARK
[5] ASTROPHYS OBSERV, I-36102 ASIAGO, ITALY
[6] OSSERV ASTRON TORINO, I-10025 TURIN, ITALY
[7] CSS, I-10128 TURIN, ITALY
[8] ASTRON RECH INST, W-6900 HEIDELBERG, GERMANY
[9] DELFT UNIV TECHNOL, FAC GEODESY, 2629 JA DELFT, NETHERLANDS
[10] SRON, 3584 CA UTRECHT, NETHERLANDS