http://xmm.esac.esa.int/docs/documents/CAL-SRN-0088-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0065-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0046-1-0.ps.gz
http://xmm.esac.esa.int/docs/documents/CAL-SRN-0014-1-0.ps.gz