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 -LAT 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 _ { stat } \pm 0.12 _ { 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 _ { stat } \pm 0.27 _ { 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 _ { 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 .