Next: Size of ACIS-2C pixels Up: Spatial linearity Previous: Spatial linearity
We consider data for a front-illuminated device exposed to 2.29 keV photons as a typical case. Correlation between the ACIS measured positions and the FAM Y values for horizontal displacement of FAM is shown at Fig. 6.17. Mean scatter of the experimental points (standard deviation) is 1.79 m. Here we should take into account that an error in FAM positioning is not less than 1 m, which results in a formal ACIS error of less than 1.5 m.
Results shown in Fig. 6.17 demonstrate that accompanying the FAM movement in the horizontal direction there is also a change in the vertical positions of ACIS. That means that the ACIS-2C camera has been installed with a rotation angle of 18 arc min around the FAM X axis.