  SuperSpec is a novel on-chip spectrometer we are developing for multi-object,
moderate resolution (R = 100 - 500), large bandwidth (~1.65:1) submillimeter
and millimeter survey spectroscopy of high-redshift galaxies. The spectrometer
employs a filter bank architecture, and consists of a series of half-wave
resonators formed by lithographically-patterned superconducting transmission
lines. The signal power admitted by each resonator is detected by a lumped
element titanium nitride (TiN) kinetic inductance detector (KID) operating at
100 - 200 MHz. We have tested a new prototype device that achieves the targeted
R = 100 resolving power, and has better detector sensitivity and optical
efficiency than previous devices. We employ a new method for measuring photon
noise using both coherent and thermal sources of radiation to cleanly separate
the contributions of shot and wave noise. We report an upper limit to the
detector NEP of $1.4\times10^{-17}$ W Hz$^{-1/2}$, within 10% of the photon
noise limited NEP for a ground-based R=100 spectrometer.
