Here you can obtain information on the past, current, and predicted future orientation of the Earth in space. The available Earth Orientation Parameters (EOP) include the coordinates of the Earth's pole (polar motion), the rotation angle about the pole (Universal Time or UT1), and celestial pole offsets (precession and nutation). Here you will also find the positions of the extragalactic radio sources which form the basis for the quasi-inertial celestial reference frame within which the EOP parameters are determined.

Earth Orientation Parameters:

• IERS Bulletin A (the National Earth Orientation Service Bulletin)
• Bulletin A Web Page
• most recent Earth Orientation Parameters (x, y, and UT1-UTC)

Celestial Reference Frame:

• Radio Optical Reference Frame (RORF)
• Radio Reference Frame Image Database (RRFID)
• Optical Image Database (OID)

GPS Data Analysis:

• IGS Data and Products (USNO contributes to the IGS Rapid, Predicted, and Ultra-Rapid products)
• IGS/BIPM Pilot Project for Time Transfer
• USNO Clock Estimates

Other useful information:

• Obtaining NEOS VLBI data
• Explanatory Supplement to IERS Bulletins A and B
• Historical differences between International Atomic Time (TAI) and Coordinated Universal Time (UTC)
• What is Earth Orientation?
• What is a leap second?

Would you like to regularly receive EOP data? If so, please fill out and submit a product request form (requires a 'forms' capable browser).