  Measurement of fusion excitation functions for stable nuclei has largely been
restricted to nuclei with significant natural abundance. Typically, to
investigate neighboring nuclei with low natural abundance has required
obtaining isotopically enriched material. This restriction often limits the
ability to perform such measurements. We report the measurement of a high
quality fusion excitation function for a $^{17}$O beam produced from unenriched
material with 0.038\% natural abundance. The measurement is enabled by using an
active thick-target approach and the accuracy of the result is validated using
its mirror nucleus $^{17}$F and resonances. The result provides important
information about the average fusion cross-section for the oxygen isotopic
chain as a function of neutron excess.
