Context :

Aims : We study the 0.57 keV ( O VII triplet ) and 0.65 keV ( O VIII ) diffuse emission generated by charge transfer collisions between solar wind ( SW ) oxygen ions and interstellar H and He neutral atoms in the inner Heliosphere .
These lines which dominate the 0.3-1.0 keV energy interval are also produced by hot gas in the galactic halo ( GH ) and possibly the Local Interstellar Bubble ( LB ) .

Methods : We developed a time-dependent model of the Solar Wind Charge-Exchange ( SWCX ) X-ray emission , based on the localization of the Solar Wind Parker spiral at each instant .
We include input SW conditions affecting three selected fields , as well as shadowing targets observed with XMM-Newton , Chandra and Suzaku satellites and calculate X-ray emission in the oxygen lines O VII and O VIII in order to determine the SWCX contamination and the residual emission to attribute to the galactic soft X-ray background .
We obtain ground level intensities and/or simulated lightcurves for each target and compare to X-ray data from the three instruments mentioned .

Results : The local 3/4 keV emission ( due essentially to O VII and O VIII ) detected in front of shadowing clouds is found to be entirely explained by the CX heliospheric emission .
No emission from the LB is needed at these energies .
The observed and modeled range of the foreground oxygen emission is 0.3-4.6 LU ( Line Units = photons cm ^ { -2 } s ^ { -1 } sr ^ { -1 } ) for OVII and 0.02-2.1 LU for OVIII depending on directions and conditions .

Using the model predictions we subtract the heliospheric contribution to the measured emission and derive the halo contribution .
We also correct for an error in the preliminary analysis of the Hubble Deep Field North ( HDFN ) .
We find intensities of 4.9 ^ { +1.29 } _ { -1.04 } LU , 6.25 ^ { +0.63 } _ { -0.98 } LU , 11.15 ^ { +2.36 } _ { -1.41 } LU for OVII and 1.41 ^ { +0.60 } _ { -0.49 } LU , 1.62 ^ { +0.35 } _ { -0.49 } LU , 1.97 ^ { +1.11 } _ { -0.71 } LU for OVIII towards the Marano Field , the Hubble Deep Field-North , and the Lockman Hole respectively .

Conclusions :