lsst.skymap  22.0.1-6-g50866e6+c057894a70
utils.py
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1 #
2 # LSST Data Management System
3 # Copyright 2008, 2009, 2010 LSST Corporation.
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5 # This product includes software developed by the
6 # LSST Project (http://www.lsst.org/).
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22 
23 __all__ = ["coordFromVec", "makeSkyPolygonFromBBox", "Index2D"]
24 
25 from typing import NamedTuple
26 import numpy
27 
28 import lsst.sphgeom
29 import lsst.geom as geom
30 
31 _TinyFloat = numpy.finfo(float).tiny
32 
33 
34 def coordFromVec(vec, defRA=None):
35  """Convert an ICRS cartesian vector to an ICRS lsst.geom.SpherePoint
36 
37  Parameters
38  ----------
39  vec : `list` of `float`
40  An ICRS catesian vector.
41  defRA : `lsst.geom.Angle` or None
42  The RA to use if the vector is too near a pole;
43  ignored if not near a pole.
44 
45  Raises
46  ------
47  RuntimeError
48  If vec too near a pole and defRA is None.
49  """
50  if abs(vec[0]) < _TinyFloat and abs(vec[1]) < _TinyFloat:
51  if defRA is None:
52  raise RuntimeError("At pole and defRA==None")
53  if vec[2] > 0:
54  decDeg = 90.0
55  else:
56  decDeg = -90.0
57  return geom.SpherePoint(defRA, decDeg*geom.degrees)
59 
60 
61 def makeSkyPolygonFromBBox(bbox, wcs):
62  """Make an on-sky polygon from a bbox and a SkyWcs
63 
64  Parameters
65  ----------
66  bbox : `lsst.geom.Box2I` or `lsst.geom.Box2D`
67  Bounding box of region, in pixel coordinates
68  wcs : `lsst.afw.geom.SkyWcs`
69  Celestial WCS
70 
71  Returns
72  -------
73  polygon : `lsst.sphgeom.ConvexPolygon`
74  On-sky region
75  """
76  pixelPoints = geom.Box2D(bbox).getCorners()
77  skyPoints = wcs.pixelToSky(pixelPoints)
78  return lsst.sphgeom.ConvexPolygon([sp.getVector() for sp in skyPoints])
79 
80 
81 class Index2D(NamedTuple):
82  """Two dimensional index for patches and cells.
83 
84  This class contains the x and y values of the location of a patch
85  within a tract, or a cell within a patch.
86 
87  Parameters
88  ----------
89  x : `int`
90  y : `int`
91  """
92  x: int
93  y: int
def coordFromVec(vec, defRA=None)
Definition: utils.py:34
def makeSkyPolygonFromBBox(bbox, wcs)
Definition: utils.py:61