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 APOGEE instrument produces roughly and up to 100 GB per night . APZIP was created to speed up data transfer from the Apache Point Observatory to the Science Archive Server (SAS) and to minimize overall disk usage. It compresses raw data cubes by taking advantage of the fact that successive reads of the detector arrays are highly similar. 2. Technical Compression Algorithm
: An average difference image is computed and subtracted from all difference images, resulting in "residual" images that are easier to compress.
The APZIP procedure uses a three-step custom algorithm to achieve an average compression factor of approximately .
: Compressed files generated by APZIP are saved with the .apz extension.
: The corresponding program APUNZIP.PRO is used to restore the raw data cubes for reduction.
: The resulting multi-extension FITS files are compressed using the FPACK utility and the lossless Rice compression algorithm . 3. Usage and Accessibility
Apzip Link
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 APOGEE instrument produces roughly and up to 100 GB per night . APZIP was created to speed up data transfer from the Apache Point Observatory to the Science Archive Server (SAS) and to minimize overall disk usage. It compresses raw data cubes by taking advantage of the fact that successive reads of the detector arrays are highly similar. 2. Technical Compression Algorithm APZIP was created to speed up data transfer
: An average difference image is computed and subtracted from all difference images, resulting in "residual" images that are easier to compress. Usage and Accessibility
The APZIP procedure uses a three-step custom algorithm to achieve an average compression factor of approximately . APZIP was created to speed up data transfer
: Compressed files generated by APZIP are saved with the .apz extension.
: The corresponding program APUNZIP.PRO is used to restore the raw data cubes for reduction.
: The resulting multi-extension FITS files are compressed using the FPACK utility and the lossless Rice compression algorithm . 3. Usage and Accessibility
