The status of LIGO installation and commissioning

LIGO is engaged in installation and commissioning of three suspended-mass i nterferometers at observatory sites in Hanford and Livingston. We are commi ssioning the first instance of any subsystem installed, prior to completion of the entire detector, so we may apply lessons learned to later installat ions. We have installed all seismic-isolation stacks, installed lasers and input optics at both observatories and we have operated both of the 2 km Fa bry-Perot cavities at Hanford, with lock times of up to 10 h.