  The PROSPECT and STEREO collaborations present a combined measurement of the
pure $^{235}$U antineutrino spectrum, without site specific corrections or
detector-dependent effects. The spectral measurements of the two highest
precision experiments at research reactors are found to be compatible with
$\chi^2/\mathrm{ndf} = 24.1/21$, allowing a joint unfolding of the prompt
energy measurements into antineutrino energy. This $\bar{\nu}_e$ energy
spectrum is provided to the community, and an excess of events relative to the
Huber model is found in the 5-6 MeV region. When a Gaussian bump is fitted to
the excess, the data-model $\chi^2$ value is improved, corresponding to a
$2.4\sigma$ significance.
