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Figure F.6: Electronic position correction tables for PSPC-C: left from top to bottom , , and , according to Eq.(F.8); right from top to bottom , , and , according to Eq.(F.9). The recorded raw detector coordinates and correspond to RAWX and RAWY in the figure.
Figure F.7: Electronic position correction tables for PSPC-B: left from top to bottom , , and , according to Eq.(F.8); right from top to bottom , , and , according to Eq.(F.9). The recorded raw detector coordinates and correspond to RAWX and RAWY in the figure.
The PSPC wires cause small-scale spatial non-linearities. This effect depends on the position as well as on the energy of the photon. A correction vector is computed using a parabola with spatially-dependent coefficients and the amplitude as variable according to Eq. (F.8) and (F.9).
Here , , and are the correction coefficients parallel to the anode wire direction while , , and denote coefficients perpendicular (``senkrecht'') to the anode wires. The correction coefficients are stored in table with 4000 elements and the electronic position correction is actually done by interpolation between two table elements (cf. Eq. (F.11)).
Figure F.6 and F.7 shows this correction for PSPC-C and PSPC-B, respectively.
There is an inconsistency in the documentation about the amplitude to be used in the correction: [Hasinger and Snowden1990] as well as Chap. 3 and [Turner et al.1995] state , whereas Chap. 8 (SASS) uses . In fact, in the creation of the correction tables no corrections had been applied, i.e., should be used; however, the differential effect between and is minor [Briel1995].
The electronic position correction in y is done similiar to the correction in x; simply replace x by y in the above formulae.
SASS source code: package PSPC, bubble CT, subroutine DCORE