Spectra and phototometry of type IIn supernova SN 1997eg are used to determine properties of the circumstellar gas lost by the presupernova during the latest 200 years before the explosion .
The analysis of narrow H \alpha and [ Fe X ] 6374 Å results in the wind velocity u = 20 km s ^ { -1 } , significantly lower than the earlier accepted value ( 160 km s ^ { -1 } ) upon the bases of the radial velocity of a blue absorption wing of the narrow H \alpha .
That high velocity of the wind in our picture is related to the preshock gas accelerated by the cosmic ray precursor .
The modelling of the circumstellar interaction results in the wind density parameter \dot { M } / u that being combined with the wind velocity suggests the presupernova mass loss rate of 1.6 \cdot 10 ^ { -3 } M _ { \odot } yr ^ { -1 } .
The wind density is consistent with the [ Fe X ] 6374 Å luminosity .
The model H \alpha luminosity also agrees with the observational value .
Recovered wind properties indicate that the presupernova at the final evolutionary stage was a massive red supergiant with a high mass loss rate , but not the LBV-supergiant as suggested earlier .