XMM-Newton Data Files Handbook

5 Calibration data: CCF

The Current Calibration File, CCF, is the collection of data sets that are available with observation data files to allow science analysis, i.e., to reduce and analyse the data collected with the scientific payload of XMM-Newton. Dedicated software (Calibration Access Layer, CAL) is available in the SAS distribution to access or visualise CCF files. The reader may refer to [10] for a detailed description of the CAL structure and functions.

The nomenclature used here is as follows:

• Current Calibration File (CCF): the collection of all the calibration files that are valid at a particular time. This is different from the collection of all the calibration files stored in the CCF repository.
  

  The current calibration file does not have a version number, and it should be seen as a view of what calibration files are valid for a time and for a specific observation date.

• Calibration data type: Broad classification of relevant function

• Calibration file or Constituent: one instance of a given calibration data type.
  

  A calibration file has an issue number and a start-of-validity date, by which it can be uniquely identified.
  

  Several calibration files can refer to the same calibration data type. They may refer to different instruments (or scope), or to different issues of the same data. Each triplet {scope, calibration type, issue} is unique.

The decision of which calibration files are relevant to a given observation is solely based on the time when the observation was made and the time of the analysis. A repository of all the CCF constituents can be found at
ftp://xmm.esac.esa.int/pub/ccf/constituents.

A more detailed description of the calibration file contents can be found in [1].