2011A&A...534A..37K

We study the bright Seyfert 1 galaxy Mrk 509 with the Reflection Grating Spectrometers (RGS) of XMM-Newton, using for the first time the RGS multi-pointing mode of XMM-Newton to constrain the properties of the outflow in this object. We obtain very accurate spectral properties from a 600ks spectrogram of Mrk 509 with excellent quality. We derive an accurate relative calibration for the effective area of the RGS and an accurate absolute wavelength calibration. We improve the method for adding time-dependent spectra and enhance the efficiency of the spectral fitting by two orders of magnitude. Taking advantage of the spectral data quality when using the new RGS multi-pointing mode of XMM-Newton, we show that the two velocity troughs previously observed in UV spectra are resolved.