Coupled Dispersive and Nondispersive Spectroscopy with the Reflection Grating Spectrometer (RGS) Experiment aboard XMM

Two of the three large collecting area telescope mirror assemblies aboard XMM feed the Reflection Grating Spectrometers (RGS). Roughly half of the light passing through those telescopes is intercepted by an array of gratings and dispersed into multiple spectral orders, which in turn illuminate a large array of back--illuminated CCD X--Ray imaging spectrometers. The RGS instruments operate continually (in the 0.3--2.0 keV band) and so large volumes of quality spectral data will be acquired. Since the RGS instruments work as long--slit spectrometers (without the slit), wavelength solutions are source position dependent and crowded or diffuse fields will present new challenges in higher dimensional datasets that are nearly guaranteed to yield interesting, if not significant, results in any observation. With the rapid approach of XMM's launch date, we will discuss some characteristics of RGS data and describe some approaches to its reduction.