  The Near-Infrared Spectrograph (NIRSpec) is one the four focal plane
instruments on the James Webb Space Telescope (JWST) which was launched on
December 25, 2021. We present the in-flight status and performance of NIRSpec's
detector system as derived from the instrument commissioning data. The
instrument features two 2048 x 2048 HAWAII-2RG sensor chip assemblies (SCAs)
that are operated at a temperature of about 42.8 K and are read out via a pair
of SIDECAR ASICs. NIRSpec supports "Improved Reference Sampling and
Subtraction" (IRS2) readout mode that was designed to meet NIRSpec's stringent
noise requirements and to reduce 1/f and correlated noise. In addition, NIRSpec
features subarrays optimized for bright object time series observations, e.g.
for the observation of exoplanet transit around bright host stars. We focus on
the dark signal as well as the read and total noise performance of the
detectors.
