http://xmm.esac.esa.int/docs/documents/CAL-SRN-0142-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0114-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0045-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0014-1-0.ps.gz