The DAL supports three file formats:
When reading an existing file, the DAL will attempt to detect the file format; in the event that a file was opened with the modify mode, the same format will be used when it is rewritten.
When creating a new file, the default output format is FITS. This behaviour may be altered by defining the environment variable SAS_FORMAT. It can have the following values (the corresponding format for each each value is also shown):
The output format of a task can be overridden with a command line option.
The data model is abstract in that it is not dependant on an underlying representation (e.g.FITS). The following table shows the mapping to FITS, DAL and deceit files.
There are restrictions imposed by FITS ... e.g. Keyword Length is limited to 8 characters.
XMM-Newton SOC -- 2021-11-30