  Robo-AO is an autonomous laser guide star adaptive optics system recently
commissioned at the Kitt Peak 2.1-m telescope. Now operating every clear night,
Robo-AO at the 2.1-m telescope is the first dedicated adaptive optics
observatory. This paper presents the imaging performance of the adaptive optics
system in its first eighteen months of operations. For a median seeing value of
$1.31^{\prime\prime}$, the average Strehl ratio is 4\% in the $i^\prime$ band
and 29\% in the J band. After post-processing, the contrast ratio under
sub-arcsecond seeing for a $2\leq i^{\prime} \leq 16$ primary star is five and
seven magnitudes at radial offsets of $0.5^{\prime\prime}$ and
$1.0^{\prime\prime}$, respectively. The data processing and archiving pipelines
run automatically at the end of each night. The first stage of the processing
pipeline shifts and adds the data using techniques alternately optimized for
stars with high and low SNRs. The second "high contrast" stage of the pipeline
is eponymously well suited to finding faint stellar companions.
