Apzip -

: The resulting multi-extension FITS files are compressed using the FPACK utility and the lossless Rice compression algorithm . 3. Usage and Accessibility

: Detector reads are converted into difference images (the first read plus difference images) to reduce dynamic range. : The resulting multi-extension FITS files are compressed

The theoretical maximum compression for APOGEE's noise levels and bit depth is approximately 2.6. In practice, APZIP’s compression of ~2.0 is considered as good as can be expected for the specific astrophysical data it handles. : The resulting multi-extension FITS files are compressed