approximateWcs¶
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lsst.meas.astrom.approximateWcs(wcs, bbox, order=3, nx=20, ny=20, iterations=3, skyTolerance=Angle(2.7777777777777781e-07, degrees), pixelTolerance=0.02, useTanWcs=False)¶ Approximate an existing WCS as a TAN-SIP WCS
The fit is performed by evaluating the WCS at a uniform grid of points within a bounding box.
Parameters: - wcs :
lsst.afw.geom.SkyWcs wcs to approximate
- bbox :
lsst.geom.Box2I the region over which the WCS will be fit
- order :
int order of SIP fit
- nx :
int number of grid points along x
- ny :
int number of grid points along y
- iterations :
int number of times to iterate over fitting
- skyTolerance :
lsst.geom.Angle maximum allowed difference in world coordinates between input wcs and approximate wcs (default is 0.001 arcsec)
- pixelTolerance :
float maximum allowed difference in pixel coordinates between input wcs and approximate wcs (default is 0.02 pixels)
- useTanWcs :
bool send a TAN version of wcs to the fitter? It is documented to require that, but I don’t think the fitter actually cares
Returns: - fitWcs :
lsst.afw.geom.SkyWcs the fit TAN-SIP WCS
- wcs :