Conversion between FITS and internal format

The FITS conversion commands INTAPE and OUTTAPE can both access FITS files on disk or directly on tape devices. Thus, it is in principle possible to use general system utilities to transfer the FITS files between disk and tape. When using operating system utilities special care must be taken to ensure that the files on the tape conform to FITS blocking specification - it is by no means obvious!

The syntax of FITS conversion commands is as follows:

INTAPE file_list id device [flag]
OUTTAPE cat[,list] device [flag] [dens,block] [type]

These are described in more detail in the following sections.

In order to save disk space, it may be desirable to compress the files. For this purpose, operating system utilities may be used (e.g. compress for UNIX). The steps to achieve this are as follows:

• Use OUTTAPE to write file to disk in FITS format.
• Compress FITS file on disk e.g. compress.
• Use system utility to save compressed file on tape e.g. tar.

To retrieve files execute the above process in reverse order.