calculateImageParallacticAngle

lsst.ip.diffim.calculateImageParallacticAngle(visitInfo, wcs)

Calculate the total sky rotation angle of an exposure.

Parameters:

visitInfo : lsst.afw.image.VisitInfo

Metadata for the exposure.

wcs : lsst.afw.geom.SkyWcs

Coordinate system definition (wcs) for the exposure.

Returns:

lsst.geom.Angle

The rotation of the image axis, East from North. Equal to the parallactic angle plus any additional rotation of the coordinate system. A rotation angle of 0 degrees is defined with North along the +y axis and East along the +x axis. A rotation angle of 90 degrees is defined with North along the +x axis and East along the -y axis.