  We present the on-orbit performance of the Colorado Ultraviolet Transit
Experiment ($CUTE$). $CUTE$ is a 6U CubeSat that launched on September 27th,
2021 and is obtaining near-ultraviolet (NUV, 2480 A -- 3306 A) transit
spectroscopy of short-period exoplanets. The instrument comprises a 20 cm
$\times$ 8 cm rectangular Cassegrain telescope, an NUV spectrograph with a
holographically ruled aberration-correcting diffraction grating, and a
passively cooled, back-illuminated NUV-optimized CCD detector. The telescope
feeds the spectrograph through an 18$'$ $\times$ 60$''$ slit. The spacecraft
bus is a Blue Canyon Technologies XB1, which has demonstrated $\leq$ 6$''$
jitter in 56% of $CUTE$ science exposures. Following spacecraft commissioning,
an on-orbit calibration program was executed to characterize the $CUTE$
instrument's on-orbit performance. The results of this calibration indicate
that the effective area of $CUTE$ is $\approx$ 19.0 -- 27.5 cm$^{2}$ and that
the average intrinsic resolution element is 2.9 A across the bandpass. This
paper describes the measurement of the science instrument performance
parameters as well as the thermal and pointing characteristics of the
observatory.
