We look for possible spectral features and systematic effects in Fermi-LAT publicly available high-energy gamma-ray data by studying photons from the Galactic centre , nearby galaxy clusters , nearby brightest galaxies , AGNs , unassociated sources , hydrogen clouds and Earth Limb .
Apart from already known 130 GeV gamma-ray excesses from the first two sources , we find no new statistically significant signal from others .
Much of our effort goes to studying Earth Limb photons .
In the energy range 30 GeV to 200 GeV the Earth Limb gamma-ray spectrum follows power-law with spectral index 2.87 \pm 0.04 at 95 % CL , in a good agreement with the PAMELA measurement of cosmic ray proton spectral index between 2.82-2.85 , confirming the physical origin of the Limb gamma-rays .
In small subsets of Earth Limb data with small photon incidence angle it is possible to obtain spectral features at different energies , including at 130 GeV , but determination of background , thus their significances , has large uncertainties in those cases .
We observe systematic 2 \sigma level differences in the Earth Limb spectra of gamma-rays with small and large incidence angles .
The behaviour of those spectral features as well as background indicates that they are likely statistical fluctuations .