• organizing operational activities for observation and data analysis, collecting and archiving appropriate data and results, and disseminating the results to meet the needs of users.

IERS consists of a Central Bureau and Coordinating Centers for each of the principal observing techniques, and it is supported by many other organizations that contribute to the tasks of observation and data processing.

The Coordinating Centers are responsible for developing and organizing the activities in each technique to meet the objectives of the service. The Central Bureau combines the various types of data collected by the service and disseminates to the user community the appropriate information on earth orientation and the terrestrial and celestial reference systems. It can include subbureaus for the accomplishment of specific tasks. The Central Bureau decides and disseminates the announcements of leap seconds in UTC and values of DUT1 to be transmitted with time signals.

The Directing Board is composed of representatives of:

• the International Astronomical Union,

• the International Association of Geodesy/International Union of Geodesy and Geophysics,

• the Federation of Astronomical and Geophysical Data Analysis Services,

• the Central Bureau, and

• each of the Coordinating Centers.

The chairperson is a member of the Directing Board, elected by the board for a term of 4 years, with the possibility of reelection for one additional term. He/she coordinates the activity of the Directing Board and is the official representative of the service at meetings of the IAU, IAG/IUGG, FAGS, and other outside organizations.

The Directing Board exercises general control over the activities of the service, including modifications to the organization and participation that would be appropriate to maintain efficiency and reliability, while taking full advantage of advances in technology and theory. Most decisions are expected to be made by consensus or by a simple majority vote. Changes in the structure, membership, and chairmanship of the Directing Board can be made at any time by a two-thirds majority.

Front Matter (R1-R12)

1. Overview (1-21)

2. Scientific Rationale For Global Networks (22-62)

3. Operational Considerations (63-88)

4. A Proposed Plan (89-105)

References (106-110)

Acronyms (111-114)

Appendix A: Review of Recent Studies (115-122)

Appendix B: IERS Charge/Mission (123-125)

Appendix C: IGS Call for Participation (126-127)

Appendix D: Economics of Campaign vs. Observatory Mode (128-130)