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# 

# LSST Data Management System 

# Copyright 2008, 2009, 2010 LSST Corporation. 

# 

# This product includes software developed by the 

# LSST Project (http://www.lsst.org/). 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU General Public License as published by 

# the Free Software Foundation, either version 3 of the License, or 

# (at your option) any later version. 

# 

# This program is distributed in the hope that it will be useful, 

# but WITHOUT ANY WARRANTY; without even the implied warranty of 

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

# GNU General Public License for more details. 

# 

# You should have received a copy of the LSST License Statement and 

# the GNU General Public License along with this program. If not, 

# see <http://www.lsstcorp.org/LegalNotices/>. 

# 

 

__all__ = ["coordFromVec"] 

 

import numpy 

 

import lsst.sphgeom 

import lsst.afw.geom as afwGeom 

 

 

_TinyFloat = numpy.finfo(float).tiny 

 

 

def coordFromVec(vec, defRA=None): 

"""Convert an ICRS cartesian vector to an ICRS lsst.geom.SpherePoint 

 

Parameters 

---------- 

vec : `list` of `float` 

An ICRS catesian vector. 

defRA : `lsst.geom.Angle` or None 

The RA to use if the vector is too near a pole; 

ignored if not near a pole. 

 

Raises 

------ 

RuntimeError 

If vec too near a pole and defRA is None. 

""" 

if abs(vec[0]) < _TinyFloat and abs(vec[1]) < _TinyFloat: 

if defRA is None: 

raise RuntimeError("At pole and defRA==None") 

if vec[2] > 0: 

decDeg = 90.0 

else: 

decDeg = -90.0 

return afwGeom.SpherePoint(defRA, decDeg*afwGeom.degrees) 

return afwGeom.SpherePoint(lsst.sphgeom.Vector3d(*vec))