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Last modified: December 2009

URL: http://cxc-newtest.cfa.harvard.edu/ciao4.2/pix_deapply_aspect.html
AHELP for CIAO 4.2

pix_deapply_aspect

Context: pixlib

Synopsis

Convert from Sky tangent coordinates to FPC by reversing the aspect solution.

Syntax

Array_Type pix_deapply_aspect( Double_Type x, Double_Type y,
Double_Type u, Double_Type v, Double_Type roll )

Description

This routine converts a position in the Sky tangent coordinate system to the Focal Plane coordinate (FPC) system. To perform this conversion the routine needs to know the aspect solution, knowledge of where the telescope was pointing at the time the photon was detected. The (x,y) values give the photon location in the Sky tangent system, in pixels, while the (u,v,roll) values give the aspect offset information, with (u,v) in pixels and roll is the roll angle in degrees. The return value is a two-element array which gives the FPC coordinates in pixels.

Notes

It is recommended that the pix_dmTanPixToWorld() and pix_TanWorldToPix() routines are used instead of pix_apply_aspect() and pix_deapply_aspect(), since the results will be more accurate.

Bugs

See the bugs page for the pixlib library on the CIAO website for an up-to-date listing of known bugs.

See Also

modules
pixlib
pixlib
pix_apply_aspect, pix_dmtanpixtoworld, pix_dmtanworldtopix

Last modified: December 2009