We describe the Zpectrometer, an ultra-wideband radio spectrometer for the Green Bank
Telescope (GBT). Observations with this instrument will be important for understanding the
star formation, metal production, and structure formation histories of the universe. The
Zpectrometer covers the full 13.5 GHz-wide Ka band with a set of analog lag correlation
spectrometers in a multi-channel correlation radiometer architecture. Its bandwidth and
stability, combined with the GBT's collecting area, enable sensitive and efficient spectral …