This application converts an Asterix data cube into a standard NDF. See Section "Notes" (below) for details of the conversion.

IN = NDF (Read)

OUT = NDF (Write)

ast2ndf ast_cube ndf_cube

This example generates NDF data cube ndf_cube (in file ndf_cube.sdf) from Asterix cube ast_cube (in file ast_cube.sdf).

This application accepts data in the format used by the Asterix package (see SUN/98). These data are cubes, with two axes comprising a regular grid of positions on the sky and the third corresponding to energy or wavelength. The data are Starlink HDS files which are very similar in format to a standard NDF. The following points apply.

• The Asterix QUALITY array is non-standard. There is no QUALITY component in the output NDF. Instead ‘bad’ or ‘null’ values are used to indicate missing or suspect values.

• The VARIANCE component is copied if it is present.

• The non-standard Asterix axis components are replaced with standard ones.

• The order of the axes is rearranged.

D.J. Allan and R.J. Vallance, 1995, in SUN/98: ASTERIX – X-ray Data Processing System, Starlink.

Kappa: AXCONV.