The XMM-Newton Optical/UV Monitor Telescope
  The XMM-OM instrument extends the spectral coverage of the XMM-Newton observatory into the ultraviolet and optical range. It provides imaging and time-resolved data on targets simultaneously with observations in the EPIC and RGS. It also has the ability to track stars in its field of view, thus providing an improved post-facto aspect solution for the spacecraft. An overview of the XMM-OM and its operation is given, together with current information on the performance of the instrument. 
K. O. Mason (1), A. A. Breeveld (1), R. Much (2), M. Carter (1), F. A.   Cordova (3), M. S. Cropper (1), J. Fordham (4), H. ...