approximateWcs¶

lsst.meas.astrom.
approximateWcs
(wcs, bbox, order=3, nx=20, ny=20, iterations=3, skyTolerance=4.84814e09 rad, pixelTolerance=0.02, useTanWcs=False)¶ Approximate an existing WCS as a TANSIP 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 TANSIP WCS
 wcs :