1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
|
# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
Contains the transformation functions for getting to/from ecliptic systems.
"""
from __future__ import (absolute_import, unicode_literals, division,
print_function)
from ... import units as u
from ..baseframe import frame_transform_graph
from ..transformations import FunctionTransform, DynamicMatrixTransform
from ..matrix_utilities import (rotation_matrix,
matrix_product, matrix_transpose)
from ..representation import CartesianRepresentation
from ... import _erfa as erfa
from .icrs import ICRS
from .gcrs import GCRS
from .ecliptic import GeocentricTrueEcliptic, BarycentricTrueEcliptic, HeliocentricTrueEcliptic
from .utils import get_jd12
from ..errors import UnitsError
def _ecliptic_rotation_matrix(equinox):
jd1, jd2 = get_jd12(equinox, 'tt')
rnpb = erfa.pnm06a(jd1, jd2)
obl = erfa.obl06(jd1, jd2)*u.radian
return matrix_product(rotation_matrix(obl, 'x'), rnpb)
@frame_transform_graph.transform(FunctionTransform, GCRS, GeocentricTrueEcliptic)
def gcrs_to_geoecliptic(gcrs_coo, to_frame):
# first get us to a 0 pos/vel GCRS at the target equinox
gcrs_coo2 = gcrs_coo.transform_to(GCRS(obstime=to_frame.equinox))
rmat = _ecliptic_rotation_matrix(to_frame.equinox)
newrepr = gcrs_coo2.cartesian.transform(rmat)
return to_frame.realize_frame(newrepr)
@frame_transform_graph.transform(FunctionTransform, GeocentricTrueEcliptic, GCRS)
def geoecliptic_to_gcrs(from_coo, gcrs_frame):
rmat = _ecliptic_rotation_matrix(from_coo.equinox)
newrepr = from_coo.cartesian.transform(matrix_transpose(rmat))
gcrs = GCRS(newrepr, obstime=from_coo.equinox)
# now do any needed offsets (no-op if same obstime and 0 pos/vel)
return gcrs.transform_to(gcrs_frame)
@frame_transform_graph.transform(DynamicMatrixTransform, ICRS, BarycentricTrueEcliptic)
def icrs_to_baryecliptic(from_coo, to_frame):
return _ecliptic_rotation_matrix(to_frame.equinox)
@frame_transform_graph.transform(DynamicMatrixTransform, BarycentricTrueEcliptic, ICRS)
def baryecliptic_to_icrs(from_coo, to_frame):
return matrix_transpose(icrs_to_baryecliptic(to_frame, from_coo))
_NEED_ORIGIN_HINT = ("The input {0} coordinates do not have length units. This "
"probably means you created coordinates with lat/lon but "
"no distance. Heliocentric<->ICRS transforms cannot "
"function in this case because there is an origin shift.")
@frame_transform_graph.transform(FunctionTransform, ICRS, HeliocentricTrueEcliptic)
def icrs_to_helioecliptic(from_coo, to_frame):
if not u.m.is_equivalent(from_coo.cartesian.x.unit):
raise UnitsError(_NEED_ORIGIN_HINT.format(from_coo.__class__.__name__))
# get barycentric sun coordinate
# this goes here to avoid circular import errors
from ..solar_system import get_body_barycentric
bary_sun_pos = get_body_barycentric('sun', to_frame.equinox)
# offset to heliocentric
heliocart = from_coo.cartesian + bary_sun_pos
# now compute the matrix to precess to the right orientation
rmat = _ecliptic_rotation_matrix(to_frame.equinox)
newrepr = heliocart.transform(rmat)
return to_frame.realize_frame(newrepr)
@frame_transform_graph.transform(FunctionTransform, HeliocentricTrueEcliptic, ICRS)
def helioecliptic_to_icrs(from_coo, to_frame):
if not u.m.is_equivalent(from_coo.cartesian.x.unit):
raise UnitsError(_NEED_ORIGIN_HINT.format(from_coo.__class__.__name__))
# first un-precess from ecliptic to ICRS orientation
rmat = _ecliptic_rotation_matrix(from_coo.equinox)
intermed_repr = from_coo.cartesian.transform(matrix_transpose(rmat))
# now offset back to barycentric, which is the correct center for ICRS
# this goes here to avoid circular import errors
from ..solar_system import get_body_barycentric
# get barycentric sun coordinate
bary_sun_pos = get_body_barycentric('sun', from_coo.equinox)
newrepr = intermed_repr - bary_sun_pos
return to_frame.realize_frame(newrepr)
|
