Dear Suzaku users,
The XIS, PIN, and GSO has difference normalization due to calibration error of an order of 10-20 %. When analyzing the data, these differences should be properly taken into account, or your spectral fitting may run into severe trouble. These values change according to the XIS and HXD gains, XRT area, and XIS and HXD response updates. In other words, the values change depending on the CALDB (and HEADAS) release.
Using the 2008-07-09 release of CALDB applied to the Version 2 data, the normalization of PIN data relative to XIS0 data is 1.16 for observations of the Crab at the XIS nominal position, and 1.18 for those at the HXD nominal position (uncertainty is ~0.015). See Suzaku Memo 2008-06 for details.
As a reference, with older calibrations, the normalization of PIN data relative to XIS0 data is 1.06-1.09 for observations of the Crab at the XIS nominal position, and 1.11-1.13 for those at the HXD nominal position. The ranges are for use of different energy bands for the PIN data. See Suzaku Memo 2007-11 for details.
The PIN-GSO issue is summarized in the page ARF file for GSO analysis.