We present a detailed analysis of the soft X-ray spectrum of the Seyfert 1 galaxy Markarian 509 taken with the XMM-Newton Reflection Grating Spectrometer .
An underlying power-law continuum and three warm absorber phases provide a good fit to the data along with a number of broad and narrow emission lines .
Our three warm absorber phases each have different ionization parameters and column densities .
We identify a low ionization , log \xi =0.89 , high outflow velocity phase producing an Fe M-shell UTA feature along with absorption from O VI and N VI .
There is an intermediate phase , log \xi =2.14 , showing absorption from H-like carbon and nitrogen and He-like neon and oxygen .
The third , high ionization , log \xi =3.26 , low outflow velocity phase contains absorption from O VIII , Ne X and highly ionized iron .
All phases are blueshifted with respect to the systemic velocity with flow velocities ranging from -60 km s ^ { -1 } to -510 km s ^ { -1 } .
The observed broad emission features have an RMS velocity of 8000 \pm 3000 km s ^ { -1 } for the C VI and O VII lines . Key words . Galaxies : active – Galaxies : Seyfert – Galaxies : individual : Mkn 509 – X-rays : galaxies – Techniques : spectroscopic – Line : identification