def test_tirs_at_least_runs():
# TODO: find an external source for a TIRS vector to test against.
# For now, just make sure it doesn't raise an exception.
ts = load.timescale()
t = ts.utc(2020, 11, 27, 15, 34)
g = Geocentric([1,2,3], [4,5,6], t=t)
g.frame_xyz_and_velocity(framelib.tirs)
def test_frame_without_spin():
ts = load.timescale()
t = ts.utc(2020, 11, 27, 15, 34)
g = Geocentric([1,2,3], [4,5,6], t=t)
# Simply test whether "None" spin raises an exception in either direction.
f = true_equator_and_equinox_of_date
r, v = g.frame_xyz_and_velocity(f)
Geocentric.from_time_and_frame_vectors(t, f, r, v)
def test_from_frame_method():
ts = load.timescale()
t = ts.utc(2020, 11, 27, 15, 34)
g1 = Geocentric([1,2,3], [4,5,6], t=t)
r, v = g1.frame_xyz_and_velocity(itrs) # which we trust: see the test above
g2 = Geocentric.from_time_and_frame_vectors(t, itrs, r, v)
assert max(abs(g2.position.au - [1,2,3])) < 2e-14
assert max(abs(g2.velocity.au_per_d - [4,5,6])) < 3e-14
# Make sure original vectors were not harmed (for example, by "+=").
assert list(g1.position.au) == [1,2,3]
assert list(g1.velocity.au_per_d) == [4,5,6]
def test_vectors():
ts = load.timescale()
t = ts.tt(2017, 1, 23, 10, 44)
planets = load('de421.bsp')
earth = planets['earth']
mars = planets['mars']
v = earth
assert str(v) == """\
Sum of 2 vectors:
+ Segment 'de421.bsp' 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
+ Segment 'de421.bsp' 3 EARTH BARYCENTER -> 399 EARTH"""
assert repr(v) == "\
<VectorSum of 2 vectors 0 SOLAR SYSTEM BARYCENTER -> 399 EARTH>"
assert str(v.at(t)) == "\
<Barycentric BCRS position and velocity at date t center=0 target=399>"
v = earth + Topos('38.9215 N', '77.0669 W', elevation_m=92.0)
assert str(v) == """\
Sum of 3 vectors:
+ Segment 'de421.bsp' 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
+ Segment 'de421.bsp' 3 EARTH BARYCENTER -> 399 EARTH
+ Topos 38deg 55' 17.4" N -77deg 04' 00.8" E"""
assert repr(v) == """\
<VectorSum of 3 vectors 0 SOLAR SYSTEM BARYCENTER -> Topos 38deg 55' 17.4" N -77deg 04' 00.8" E>"""
print(str(v.at(t)))
assert str(v.at(t)) == """\
<Barycentric BCRS position and velocity at date t center=0 \
target=Topos 38deg 55' 17.4" N -77deg 04' 00.8" E>"""
v = earth - mars
assert str(v) == """\
Sum of 4 vectors:
- Segment 'de421.bsp' 4 MARS BARYCENTER -> 499 MARS
- Segment 'de421.bsp' 0 SOLAR SYSTEM BARYCENTER -> 4 MARS BARYCENTER
+ Segment 'de421.bsp' 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
+ Segment 'de421.bsp' 3 EARTH BARYCENTER -> 399 EARTH"""
assert repr(v) == "\
<VectorSum of 4 vectors 499 MARS -> 399 EARTH>"
assert str(v.at(t)) == "\
<Geometric ICRS position and velocity at date t center=499 target=399>"
geocentric = Geocentric([0,0,0])
assert geocentric.center == 399
def test_vectors():
ts = load.timescale()
t = ts.tt(2017, 1, 23, 10, 44)
planets = load('de421.bsp')
earth = planets['earth']
mars = planets['mars']
v = earth
assert str(v) == """\
Sum of 2 vectors:
+ Segment 'de421.bsp' 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
+ Segment 'de421.bsp' 3 EARTH BARYCENTER -> 399 EARTH"""
assert repr(v) == "\
<VectorSum of 2 vectors 0 SOLAR SYSTEM BARYCENTER -> 399 EARTH>"
assert str(v.at(t)) == "\
<Barycentric BCRS position and velocity at date t center=0 target=399>"
v = earth - mars
assert str(v) == """\
Sum of 4 vectors:
- Segment 'de421.bsp' 4 MARS BARYCENTER -> 499 MARS
- Segment 'de421.bsp' 0 SOLAR SYSTEM BARYCENTER -> 4 MARS BARYCENTER
+ Segment 'de421.bsp' 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
+ Segment 'de421.bsp' 3 EARTH BARYCENTER -> 399 EARTH"""
assert repr(v) == "\
<VectorSum of 4 vectors 499 MARS -> 399 EARTH>"
assert str(v.at(t)) == "\
<Geometric ICRS position and velocity at date t center=499 target=399>"
geocentric = Geocentric([0, 0, 0])
assert geocentric.center == 399
def test_vectors():
ts = load.timescale()
t = ts.tt(2017, 1, 23, 10, 44)
planets = load('de421.bsp')
earth = planets['earth']
mars = planets['mars']
v = earth
assert str(v) == """\
Sum of 2 vectors:
'de421.bsp' segment 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
'de421.bsp' segment 3 EARTH BARYCENTER -> 399 EARTH"""
assert repr(v) == """\
<VectorSum of 2 vectors:
'de421.bsp' segment 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
'de421.bsp' segment 3 EARTH BARYCENTER -> 399 EARTH>"""
assert str(v.at(t)) == "\
<Barycentric BCRS position and velocity at date t center=0 target=399>"
v = earth + Topos('38.9215 N', '77.0669 W', elevation_m=92.0)
assert str(v) == """\
Sum of 3 vectors:
'de421.bsp' segment 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
'de421.bsp' segment 3 EARTH BARYCENTER -> 399 EARTH
Geodetic 399 EARTH -> IERS2010 latitude 38deg 55' 17.4" N longitude -77deg 04' 00.8" E elevation 92 m"""
assert repr(v) == """\
<VectorSum of 3 vectors:
'de421.bsp' segment 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
'de421.bsp' segment 3 EARTH BARYCENTER -> 399 EARTH
Geodetic 399 EARTH -> IERS2010 latitude 38deg 55' 17.4" N longitude -77deg 04' 00.8" E elevation 92 m>"""
assert str(v.at(t)) == """\
<Barycentric BCRS position and velocity at date t center=0 target=IERS2010 latitude 38deg 55' 17.4" N longitude -77deg 04' 00.8" E elevation 92 m>"""
v = earth - mars
assert str(v) == """\
Sum of 4 vectors:
Reversed 'de421.bsp' segment 499 MARS -> 4 MARS BARYCENTER
Reversed 'de421.bsp' segment 4 MARS BARYCENTER -> 0 SOLAR SYSTEM BARYCENTER
'de421.bsp' segment 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
'de421.bsp' segment 3 EARTH BARYCENTER -> 399 EARTH"""
assert repr(v) == """\
<VectorSum of 4 vectors:
Reversed 'de421.bsp' segment 499 MARS -> 4 MARS BARYCENTER
Reversed 'de421.bsp' segment 4 MARS BARYCENTER -> 0 SOLAR SYSTEM BARYCENTER
'de421.bsp' segment 0 SOLAR SYSTEM BARYCENTER -> 3 EARTH BARYCENTER
'de421.bsp' segment 3 EARTH BARYCENTER -> 399 EARTH>"""
assert str(v.at(t)) == "\
<ICRF position and velocity at date t center=499 target=399>"
geocentric = Geocentric([0, 0, 0])
assert geocentric.center == 399
#!/usr/bin/env python
from skyfield.api import EarthSatellite
from skyfield.api import load
from skyfield.positionlib import Geocentric
from skyfield.units import Angle
ts = load.timescale()
# Time used to find correct satellite
t = ts.utc(2020, 3, 18, 6, 17, 23.0)
# Coordinates used to find correct satellite
loc = Geocentric([-393.9579313710918, -4609.1758828158, -4905.812181143784])
stations = load.tle_file('wheres_the_sat.tle')
print('Loaded', len(stations), 'stations')
# Zero degrees separation
nada = Angle(degrees=0)
# Iterate over stations looking for a collision (zero degrees separation)
for station in stations:
geocentric = station.at(t)
if geocentric.separation_from(loc).degrees == nada.degrees:
# Found a collision
print(station.name)
tgt = station
# Time used to find next waypoint
t2 = ts.utc(2020, 3, 18, 22, 44, 49.0)
# Coordinates of next waypoint
geocentric = tgt.at(t2)