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This IDL facility provides a means to rotate a set of 3D position vectors (and their Stokes parameters Q and U) between to astrophysical coordinate systems or by an arbitrary rotation.

Location in HEALPix directory tree: src/idl/misc/


IDL> Outvec = ROTATE_COORD( Invec [, Inco=, Outco=, Euler_Matrix=, Stokes_Parameters=] )


input, array of size (n,3) : set of 3D position vectors
output, array of size (n,3) : rotated 3D vectors
input, character string (either 'Q' or 'C': equatorial, 'G': galactic or 'E': ecliptic) describing the input coordinate system
input, character string (see above) describing the output coordinate system.
Can not be used together with Euler_Matrix
input, array of size (3,3). Euler Matrix describing the rotation to apply to vectors. default:unity : no rotation.
Can not be used together with a change in coordinates.
input and output, array of size (n, 2) : values of the Q and U Stokes parameters on the sphere for each of the input position vector. Q and U are defined wrt the local parallel and meridian and are therefore transformed in a non trivial way in case of rotation


rotate_coord is a generalisation of the Astro library routine skyconv. It allows a rotation of 3D position vectors between two standard astronomic coordinates system but also an arbitrary rotation described by its Euler Matrix. It can also be applied to compute the effect of a rotation on the linear polarization Stokes parameters (Q and U) expressed in local coordinates system at the location of each of the input 3D vectors.


This section lists the routines related to rotate_coord

version 6.1 or more is necessary to run rotate_coord.
constructs the Euler Matrix for a set of three angles and three axes of rotation

Eric Hivon 2010-06-18
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