Refer to the XMM-Newton Users' Handbook
links) for complete information on XMM-Newton instrumentation.
European Photon Imaging Camera (EPIC) CCDs
The EPIC CCDs are designed to exploit the full design range of the X-ray mirrors, 0.1-15 keV. They provide energy resolution at 6.5 keV of E/dE~50, and their positional resolution is sufficient to resolve the mirror performance of 6 arc seconds FWHM (15 arc seconds HEW). A variety of data collection modes are provided which trade imaging performance against timing resolution and maximum count rate. A selection of filters mounted on a wheel in front of each camera allows the rejection of long wavelength optical and UV radiation in such a way as to optimize the low energy response of the instrument.
Two of the EPIC instruments on XMM-Newton consist of arrays of Metal-Oxide-Silicon (MOS) technology, X-ray-sensitive CCD arrays. The third EPIC detector is a fully depleted PN CCD. The combination of these detectors exploits the full design energy range of the X-ray mirrors with moderate energy resolution.
The MOS CCDs are front illuminated 600x600 pixel devices from EEV. The physical size of each pixel is 40Ám, corresponding to 1.1 arc seconds on the sky. There are seven CCD chips with one in the center of the field of view with the other six surrounding it. The CCDs are offset from one another to match the curvature of the focal plane.
Reflection Grating Spectrometer
Reflection Grating Spectrometers (RGS) are included on two of the three XMM-Newton X-ray telescopes. These consist of Reflection Grating Assemblies (RGAs) and RGS Focal Cameras (RFCs). The RGS provides high spectral resolution (E/dE from 200 to 800) X-ray spectroscopy over the energy range 0.35-2.5 keV (5-35 ┼). The RGAs intercept about 50% of the X-rays passing through the mirrors. The reflected X-rays are directed onto linear arrays of 9 MOS chips forming the RFC.
The high throughput of the XMM-Newton telescopes allows the RGS to perform detailed measurements of emission and absorption features in a large variety of stellar, interstellar and extragalactic hot, ionized plasmas. Compared to previous missions, this greatly enhances the use of line diagnostics in understanding cosmic X-ray sources, and leads to the determination of chemical composition, ion and elemental abundances, and the electron temperature and density distributions.
The Optical Monitor (OM) is co-aligned with the X-ray telescopes, providing simultaneous UV/optical/X-ray observations. The instrument consists of a 30 cm Ritchey-Chretien telescope feeding a compact image-intensified photon-counting detector. The detector operates in the UV and the blue region of the optical spectrum. Since the majority of X-ray sources are variable, the optical monitor allows the observer to know the optical state of the X-ray object they are viewing.
The Optical Monitor can provide spectral resolution by the use of broad- and narrow-band filters contained within a filter wheel, plus there are also two grisms in the filter wheel for low resolution spectroscopy. The spatial pixel size in normal operation is 1 arc second and the limiting sensitivity is B=24 for a star viewed with the detector in unfiltered light.
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