S-1 apply orbit file problem

  1. Before applying orbit file,I have downloaded the “.EOF” file from the website and put it into the required file"C:\Users\w.snap\auxdata\Orbits\Sentinel-1\POEORB\S1B\2017\04",but it still cannot run correctly and show cannot find the orbit file.
    how should i do next?
    2.And what does the "polynomial degree "mean?

the tool actually downloads the orbit files itself, you normally do not need to copy it there. But SNAP requires internet connection and must not be blocked by a firewall or anthing like that.

The orbit file could also be that of a restituted orbit (if the image has been processed NRT). It is less precise or could also be called a predicted orbit. https://qc.sentinel1.eo.esa.int/aux_resorb/.
For the degree of the polynomial, work with the suggestion. It is the interpolation function for the orbit state vector (position and velocity of the satellite at the time of image acquisition).

Restituted orbits are already very good, Precise orbits are better but not by much. In my opinion the precise orbits are only recommended for InSAR-applications.

thanks a lot

my appreciate