  We report the first high-significance GeV gamma-ray detections of supernova
remnants HESS J1731-347 and SN 1006, both of which have been previously
detected by imaging atmospheric Cherenkov Telescopes above 1 TeV. Using 8 years
of Fermi Pass 8 data at energies between 1 GeV and 2 TeV, we detect emission at
the position of HESS J1731-347 with a significance of $\sim 5\sigma$ and a
spectral index of $\Gamma = 1.66 \pm 0.16_{\rm stat} \pm 0.12_{\rm syst}$. The
hardness of the index and the good connection with the TeV spectrum of HESS
J1731-347 support an association between the two sources. We also confirm the
detection of SN 1006 at $\sim 6\sigma$ with a spectral index of $\Gamma = 1.79
\pm 0.17_{\rm stat} \pm 0.27_{\rm syst}$. The northeast (NE) and southwest (SW)
limbs of SN 1006 were also fit separately, resulting in the detection of the NE
region ($\Gamma = 1.47 \pm 0.26_{\rm stat}$) and the non-detection of the SW
region. The significance of different spectral components for the two limbs is
$3.6\sigma$, providing first indications of an asymmetry in the GeV
$\gamma$-ray emission.
