[1] UNIV TASMANIA,DEPT PHYS,HOBART,TAS 7001,AUSTRALIA
[2] UNIV LEICESTER,DEPT ASTRON,LEICESTER LE1 7RH,ENGLAND
[3] ROYAL OBSERV,EDINBURGH EH9 3HJ,MIDLOTHIAN,SCOTLAND
[4] HATFIELD POLYTECH,DEPT PHYS,HATFIELD AL10 9AB,HERTS,ENGLAND
[5] UNIV MANCHESTER,NUFFIELD RADIO ASTRON LABS,MACCLESFIELD SK11 9DL,CHESHIRE,ENGLAND