IERS Earth Orientation Data (EOP) Policy

The data offered by the International Earth Rotation and Reference Systems Service (IERS), including Bulletin A and Bulletin C (DUT1 predictions), are provided for users in science, engineering, and other applications. 

Use is generally free on the condition of proper acknowledgement:
"Data provided by the International Earth Rotation and Reference Systems Service (IERS)."

For more information, visit https://www.iers.org/