4.2.3.2 LUX FITS File Format

FITS stands for Flexible Image Transport System and is a file format developed by the astronomical community for data exchange and storage. For general information, see the FITS Support Office home page at http://fits.gsfc.nasa.gov/fits_home.html.

An LUX FITS file containing uncompressed data has the standard SIMPLE, BITPIX, NAXIS, and NAXISn records, and any general user-specified header text is placed on one or more COMMENT lines beyond the last NAXISn record.

For LUX FITS file that contain compressed data we define a few LUX-specific FITS keywords. A typical example of the header of such a file is displayed below.

SIMPLE  =                    T / LUX Rice compressed
BITPIX  =                    8
NAXIS   =                    1
NAXIS1  =               217750
COMPRESS= 'RICE    ' / used type of compression
UBITPIX =                   16 / BITPIX of uncompressed data
UNAXIS  =                    2 / NAXIS of uncompressed data
UNAXIS1 =                  464 / dimension of uncompressed data
UNAXIS2 =                  438 / dimension of uncompressed data
COMMENT = user-defined header text
END

The BITPIX, NAXIS, and NAXISn keywords refer to the actual data in the rest of the FITS file, as the standard demands. In this case, 217750 bytes of compressed data follow. The type of compression is described by the COMPRESS line, which may currently hold either of the values 'RICE ' for Rice compression without run-length encoding, and 'RICE RLE ' for Rice compression with run-length encoding. The type and dimensions of the uncompressed data are indicated by the lines with the U keywords, and any general user-defined header text is stored on one or more COMMENT lines.