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F.5 Electronic Position Correction (EPC)

   figure8488
Figure F.6: Electronic position correction tables for PSPC-C: left from top to bottom tex2html_wrap_inline18481 , tex2html_wrap_inline18483 , and tex2html_wrap_inline18485 , according to Eq.(F.8); right from top to bottom tex2html_wrap_inline18487 , tex2html_wrap_inline18489 , and tex2html_wrap_inline18491 , according to Eq.(F.9). The recorded raw detector coordinates tex2html_wrap_inline18493 and tex2html_wrap_inline18495 correspond to RAWX and RAWY in the figure.

   figure8496
Figure F.7: Electronic position correction tables for PSPC-B: left from top to bottom tex2html_wrap_inline18497 , tex2html_wrap_inline18499 , and tex2html_wrap_inline18501 , according to Eq.(F.8); right from top to bottom tex2html_wrap_inline18503 , tex2html_wrap_inline18505 , and tex2html_wrap_inline18507 , according to Eq.(F.9). The recorded raw detector coordinates tex2html_wrap_inline18509 and tex2html_wrap_inline18511 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).

   eqnarray8506

Here tex2html_wrap_inline18513 , tex2html_wrap_inline18515 , and tex2html_wrap_inline18517 are the correction coefficients parallel to the anode wire direction while tex2html_wrap_inline18519 , tex2html_wrap_inline18521 , and tex2html_wrap_inline18523 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 tex2html_wrap_inline18525 , whereas Chap. 8 (SASS) uses tex2html_wrap_inline18527 . In fact, in the creation of the correction tables no corrections had been applied, i.e., tex2html_wrap_inline18529 should be used; however, the differential effect between tex2html_wrap_inline18531 and tex2html_wrap_inline18533 is minor [Briel1995].

  eqnarray8520

Parameters:

The electronic position correction in y is done similiar to the correction in x; simply replace x by y in the above formulae.

Remarks:

SASS source code: package PSPC, bubble CT, subroutine DCORE

SASS files:


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Next: F.6 Correction of Spatial Up: Calibration Files for Standard Previous: F.4 Temporal Gain Correction

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