def test_appendix_c_satellite():
ts = api.load.timescale()
lines = appendix_c_example.splitlines()
sat = EarthSatellite(lines[1], lines[2], lines[0], ts)
jd_epoch = sat.model.jdsatepoch + sat.model.jdsatepochF
three_days_later = jd_epoch + 3.0
offset = ts.tt(jd=three_days_later)._utc_float() - three_days_later
t = ts.tt(jd=three_days_later - offset)
# First, a crucial sanity check (which is, technically, a test of
# the `sgp4` package and not of Skyfield): are the right coordinates
# being produced by our Python SGP4 propagator for this satellite?
rTEME, vTEME, error = sat._position_and_velocity_TEME_km(t)
# TODO: This used to be accurate to within 1e-8 but lost precision
# with the move to SGP4 2.0. Is the difference an underlying change
# in the algorithm and its results? Or something else?
epsilon = 1e-4
assert abs(-9060.47373569 - rTEME[0]) < epsilon
assert abs(4658.70952502 - rTEME[1]) < epsilon
assert abs(813.68673153 - rTEME[2]) < epsilon
# TODO: Similar to the above, this used to be 1e-9.
epsilon = 1e-8
assert abs(-2.232832783 - vTEME[0]) < epsilon
assert abs(-4.110453490 - vTEME[1]) < epsilon
assert abs(-3.157345433 - vTEME[2]) < epsilon
def test_appendix_c_satellite():
lines = appendix_c_example.splitlines()
ts = api.load.timescale()
sat = EarthSatellite(lines[1], lines[2], lines[0], ts)
t = ts.tt_jd(sat.epoch.whole + 3.0, sat.epoch.tt_fraction)
# First, a crucial sanity check (which is, technically, a test of
# the `sgp4` package and not of Skyfield): are the right coordinates
# being produced by our Python SGP4 propagator for this satellite?
rTEME, vTEME, error = sat._position_and_velocity_TEME_km(t)
# TODO: This used to be accurate to within 1e-8 but lost precision
# with the move to SGP4 2.0. Is the difference an underlying change
# in the algorithm and its results? Or something else?
epsilon = 1e-4
assert abs(-9060.47373569 - rTEME[0]) < epsilon
assert abs(4658.70952502 - rTEME[1]) < epsilon
assert abs(813.68673153 - rTEME[2]) < epsilon
# TODO: Similar to the above, this used to be 1e-9. Then the Time
# object started storing UTC as seconds, and it got worse.
epsilon = 5e-8
assert abs(-2.232832783 - vTEME[0]) < epsilon
assert abs(-4.110453490 - vTEME[1]) < epsilon
assert abs(-3.157345433 - vTEME[2]) < epsilon
def test_appendix_c_satellite():
lines = appendix_c_example.splitlines()
sat = EarthSatellite(lines[1], lines[2], lines[0])
ts = api.load.timescale()
jd_epoch = sat.model.jdsatepoch
three_days_later = jd_epoch + 3.0
offset = ts.tt(jd=three_days_later)._utc_float() - three_days_later
t = ts.tt(jd=three_days_later - offset)
# First, a crucial sanity check (which is, technically, a test of
# the `sgp4` package and not of Skyfield): are the right coordinates
# being produced by our Python SGP4 propagator for this satellite?
rTEME, vTEME, error = sat._position_and_velocity_TEME_km(t)
assert abs(-9060.47373569 - rTEME[0]) < 1e-8
assert abs(4658.70952502 - rTEME[1]) < 1e-8
assert abs(813.68673153 - rTEME[2]) < 1e-8
assert abs(-2.232832783 - vTEME[0]) < 1e-9
assert abs(-4.110453490 - vTEME[1]) < 1e-9
assert abs(-3.157345433 - vTEME[2]) < 1e-9
def test_appendix_c_satellite():
lines = appendix_c_example.splitlines()
sat = EarthSatellite(lines[1], lines[2], lines[0])
ts = api.load.timescale()
jd_epoch = sat.model.jdsatepoch
three_days_later = jd_epoch + 3.0
offset = ts.tt(jd=three_days_later)._utc_float() - three_days_later
t = ts.tt(jd=three_days_later - offset)
# First, a crucial sanity check (which is, technically, a test of
# the `sgp4` package and not of Skyfield): are the right coordinates
# being produced by our Python SGP4 propagator for this satellite?
rTEME, vTEME, error = sat._position_and_velocity_TEME_km(t)
assert abs(-9060.47373569 - rTEME[0]) < 1e-8
assert abs(4658.70952502 - rTEME[1]) < 1e-8
assert abs(813.68673153 - rTEME[2]) < 1e-8
assert abs(-2.232832783 - vTEME[0]) < 1e-9
assert abs(-4.110453490 - vTEME[1]) < 1e-9
assert abs(-3.157345433 - vTEME[2]) < 1e-9
