Using the HEGRA system of imaging atmospheric Cherenkov telescopes , a region of the Galactic plane ( -10 ^ { \circ } < b < 5 ^ { \circ } , 38 ^ { \circ } < l < 43 ^ { \circ } ) was surveyed for TeV gamma-ray emission , both from point sources and of diffuse nature .
The region covered includes 15 known pulsars , 6 known supernova remnants ( SNR ) and one unidentified EGRET source .
No evidence for emission from point sources was detected ; upper limits are typically below 0.1 Crab units for the flux above 1 TeV .
For the diffuse gamma-ray flux from the Galactic plane , an upper limit of 6.1 \cdot 10 ^ { -15 } ph cm ^ { -2 } s ^ { -1 } sr ^ { -1 } MeV ^ { -1 } was derived under the assumption that the spatial distribution measured by the EGRET instrument extends to the TeV regime .
This upper flux limit is a factor of about 1.5 larger than the flux expected from the ensemble of gamma-ray unresolved Galactic cosmic ray sources .