Besides its three X-ray telescopes, XMM-Newton also has a co-aligned 30-cm optical/UV telescope (OM), providing for the first time strictly simultaneous observations in the X-ray and optical/UV regime from a single platform. A summary of OM's salient properties is provided in Table 15. Although small in size, the OM is a powerful instrument because of the absence of atmospheric extinction, diffraction and background. It has three optical and three UV filters over the wavelength range from 180 to 600 nm. Images of the central part of the X-ray field of view with a resolution of ca. (depending on instrument configuration), low-resolution grism spectra of the optical counterparts of X-ray sources or high time-resolution photometry can be obtained. Due to the extreme sensitivity of the detector, the OM is well suited for observations of faint sources. However, observations of optically bright sources would cause permanent damage to the detector ( ca. 7.4 mag, for an A0 star with the V filter), thus, the OM can not be used if a bright optical source is in the field. The OM is a photon-counting instrument, therefore, as explained below, objects with high photon rates, even within the safety limits, will produce poor quality data.
|Total bandwidth||180 - 600 nm|
|Spectral bandwidth||180 - 600 nm|
|Sensitivity limit||20.7 mag|
|Field of view||ca.|
|Pixel size||0.476513 arcsec/pxl|
|Timing resolution||0.5 s|