The Royal Observatory at Brussels will take over responsibility for compiling relative sunspot numbers by the end of this year, according to J. O. Stenflo, director of the Swiss Federal Astronomical Observatory in Zurich. Until this year the numbers, one of the oldest continuous series of astronomical data, have been produced at Zurich. Stenflo has directed the Zurich observatory to discontinue the service by the end of this year.
The indexes from both observatories will be produced in parallel, beginning in July. The new numbers will be designated R index I (R stands for ‘relative sunspot number;’ I stands for ‘International.’) The old series was labeled R index Z.