http://xmm.esac.esa.int/docs/documents/CAL-SRN-0212-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0171-1-1.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0143-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0108-1-0.ps.gz