The NIST project for the electronic realization of the kilogram

The project Electronic Realization of the Kilogram has rebuilt the National Institute of Standards and Technology (NIST) watt balance, which has been fully operational for nine months. Short-term noise is at an all-time low with overnight runs exhibiting standard deviations of parts in 10/sup 8/. Recent improvements are discussed that have led to this enhanced performance, as are several significant error tests. Present watt results (i.e., Planck's constant) are now within 1 /spl mu/W/W of CODATA values, but error checking to report a more precise value has not been completed.