def test_rotating_vector_into_frame():
et_seconds = 259056665.1855896
ts = load.timescale()
t = ts.tdb_jd(T0 + et_seconds / 3600. / 24.0)
pc = PlanetaryConstants()
pc.read_text(load('moon_080317.tf'))
pc.read_binary(load('moon_pa_de421_1900-2050.bpc'))
# Example from "moon_080317.tf" (the raw vector is taken from a
# tweaked version of the script in the file that uses "J2000"):
vector = ICRF(
np.array([
2.4798273371071659e+05, -2.6189996683651494e+05,
-1.2455830876097400e+05
]) / AU_KM)
vector.t = t
meter = 1e-3
frame = pc.build_frame_named('MOON_PA_DE421')
result = vector.frame_xyz(frame)
assert max(abs(result.km - [379908.634, 33385.003, -12516.8859])) < meter
relative_frame = pc.build_frame_named('MOON_ME_DE421')
result = vector.frame_xyz(relative_frame)
assert max(abs(result.km - [379892.825, 33510.118, -12661.5278])) < meter
def test_separation_from_on_two_array_values():
p0 = ICRF(([1,1], [0,0], [0,0]))
p1 = ICRF(([0,-1], [1,0], [0,0]))
sep = p0.separation_from(p1)
d = sep._degrees
assert len(d) == 2
assert d[0] == 90.0
assert d[1] == 180.0
def test_subtraction():
p0 = ICRF((10, 20, 30), (40, 50, 60), center=0, target=499)
p1 = ICRF((1, 2, 3), (4, 5, 6), center=0, target=399)
p = p0 - p1
assert p.center == 399
assert p.target == 499
assert isinstance(p, Geocentric)
assert tuple(p.position.au) == (9, 18, 27)
assert tuple(p.velocity.au_per_d) == (36, 45, 54)
def test_frame_rotations_for_mean_of_date():
ts = api.load.timescale()
t = ts.utc(2020, 11, 21)
p = ICRF((1.1, 1.2, 1.3), t=t)
lat, lon, distance1 = p.frame_latlon(true_equator_and_equinox_of_date)
# Verify that the frame_latlon() coordinates match those from the
# more conventional radec() call.
ra, dec, distance2 = p.radec(epoch='date')
assert abs(lat.arcseconds() - dec.arcseconds()) < 1e-6
assert abs(lon.arcseconds() - ra.arcseconds()) < 1e-6
assert abs(distance1.au - distance2.au) < 1e-15
# Now that we know the coordinates are good, we can use them to
# rebuild a trusted x,y,z vector with which to test frame_xyz().
x1, y1, z1 = from_spherical(distance1.au, lat.radians, lon.radians)
x2, y2, z2 = p.frame_xyz(true_equator_and_equinox_of_date).au
assert abs(x1 - x2) < 1e-15
assert abs(y1 - y2) < 1e-15
assert abs(z1 - z2) < 1e-15
def test_J2000_ecliptic_coordinates_with_and_without_a_time_array():
p0 = ICRF((1, 0, 0))
p1 = ICRF((0, 1, 0))
p2 = ICRF(((1, 0), (0, 1), (0, 0)))
lat0, lon0, distance0 = p0.ecliptic_latlon(epoch=None)
lat1, lon1, distance1 = p1.ecliptic_latlon(epoch=None)
lat2, lon2, distance2 = p2.ecliptic_latlon(epoch=None)
assert lat2.degrees[0] == lat0.degrees
assert lat2.degrees[1] == lat1.degrees
assert lon2.degrees[0] == lon0.degrees
assert lon2.degrees[1] == lon1.degrees
assert distance2.au[0] == distance0.au
assert distance2.au[1] == distance1.au
def get_probe_coords(hip_id, distance):
# set timezone + load planet info
utcTZ = timezone("UTC")
local_tz = get_localzone()
ts = load.timescale()
planets = load('de421.bsp')
# get time of observation and locations of observation
t = ts.from_datetime(datetime(2020, 11, 9, 00, 00, tzinfo=utcTZ))
sun = planets['sun']
earth = planets['earth']
# load in the hipparcos data
with load.open(hipparcos.URL) as f:
df = hipparcos.load_dataframe(f)
# # match on star coords
# ra_inds = []
# for ind, cat_ra in enumerate(df['ra_degrees'].values):
# if isclose(cat_ra, ra_star, rel_tol=1e-2):
# ra_inds.append(ind)
# dec_inds = []
# for ind, cat_dec in enumerate(df['dec_degrees'].values):
# if isclose(cat_dec, dec_star, rel_tol=1e-2):
# dec_inds.append(ind)
# # find where ra & dec match within tolerance
# sets = set(ra_inds).intersection(set(dec_inds))
# inds = [x for x in iter(sets)]
# print(inds)
# just take the first one for now
the_star = Star.from_dataframe(df.loc[hip_id])
# "observe" the star from Earth
starPosObj = earth.at(t).observe(the_star)
ra, dec, dist = starPosObj.radec()
# get coords of opposite point on the sky
ra = ((ra._degrees + 180.0) % 360) * (24.0 / 360.0)
dec = -1.0 * dec._degrees
# get coords of the probe and return ra dec in degree
probe = position_of_radec(ra, dec, distance, t=t)
sunPosObj = earth.at(t).observe(sun)
inverseSunCoord = -1.0 * sunPosObj.position.au
probeCoord = probe.position.au
probeDir = ICRF(probeCoord + inverseSunCoord).radec()
return probeDir[0]._degrees, probeDir[1]._degrees
def test_dynamic_ecliptic_coordinates_with_and_without_a_time_array():
ts = api.load.timescale()
t = ts.utc(1980)
p0 = ICRF((1, 0, 0))
p1 = ICRF((0, 1, 0))
p2 = ICRF(((1, 0), (0, 1), (0, 0)))
lat0, lon0, distance0 = p0.ecliptic_latlon(epoch=t)
lat1, lon1, distance1 = p1.ecliptic_latlon(epoch=t)
lat2, lon2, distance2 = p2.ecliptic_latlon(epoch=t)
assert lat2.degrees[0] == lat0.degrees
assert lat2.degrees[1] == lat1.degrees
assert lon2.degrees[0] == lon0.degrees
assert lon2.degrees[1] == lon1.degrees
assert distance2.au[0] == distance0.au
assert distance2.au[1] == distance1.au
def test_separation_from_on_an_array_and_a_scalar():
p0 = ICRF(([1,0], [0,1], [0,0]))
p1 = ICRF((0, 0, 1))
sep = p0.separation_from(p1)
d = sep._degrees
assert len(d) == 2
assert d[0] == 90.0
assert d[1] == 90.0
# And the other way around:
sep = p1.separation_from(p0)
d = sep._degrees
assert len(d) == 2
assert d[0] == 90.0
assert d[1] == 90.0
def test_J2000_ecliptic_coordinates_with_and_without_a_time_array():
p0 = ICRF((1,0,0))
p1 = ICRF((0,1,0))
p2 = ICRF(((1, 0),
(0, 1),
(0, 0)))
lat0, lon0, distance0 = p0.ecliptic_latlon(epoch=None)
lat1, lon1, distance1 = p1.ecliptic_latlon(epoch=None)
lat2, lon2, distance2 = p2.ecliptic_latlon(epoch=None)
assert lat2.degrees[0] == lat0.degrees
assert lat2.degrees[1] == lat1.degrees
assert lon2.degrees[0] == lon0.degrees
assert lon2.degrees[1] == lon1.degrees
assert distance2.au[0] == distance0.au
assert distance2.au[1] == distance1.au
def test_dynamic_ecliptic_coordinates_with_and_without_a_time_array():
ts = api.load.timescale()
t = ts.utc(1980)
p0 = ICRF((1,0,0))
p1 = ICRF((0,1,0))
p2 = ICRF(((1, 0),
(0, 1),
(0, 0)))
lat0, lon0, distance0 = p0.ecliptic_latlon(epoch=t)
lat1, lon1, distance1 = p1.ecliptic_latlon(epoch=t)
lat2, lon2, distance2 = p2.ecliptic_latlon(epoch=t)
assert lat2.degrees[0] == lat0.degrees
assert lat2.degrees[1] == lat1.degrees
assert lon2.degrees[0] == lon0.degrees
assert lon2.degrees[1] == lon1.degrees
assert distance2.au[0] == distance0.au
assert distance2.au[1] == distance1.au
#!/usr/bin/env python
from skyfield.positionlib import ICRF
from skyfield.api import load, Topos
ts = load.timescale()
t = ts.now()
observer = Topos(latitude_degrees=52.8344,
longitude_degrees=6.3785,
elevation_m=10.0)
p = ICRF([0.0, 0.0, 0.0], observer_data=observer, t=t)
q = p.from_altaz(alt_degrees=30.0, az_degrees=30.0)
print(p, q)
def test_separation_from_on_scalar():
p0 = ICRF((1, 0, 0))
p1 = ICRF((0, 1, 0))
assert str(p0.separation_from(p1)) == '90deg 00\' 00.0"'
#!/usr/bin/env python from skyfield.positionlib import ICRF from skyfield.api import load,Topos ts=load.timescale() t=ts.now() observer=Topos(latitude_degrees=52.8344,longitude_degrees=6.3785,elevation_m=10.0) p=ICRF([0.0,0.0,0.0],observer_data=observer,t=t) q=p.from_altaz(alt_degrees=30.0,az_degrees=30.0) print(p,q)
def test_ecliptic_xyz_with_no_epoch():
p = ICRF(_deep)
x, y, z = p.ecliptic_xyz().au
assert x.shape == y.shape == z.shape == (1, 1)
vrad = np.sqrt(C3temp + 2. * GMsun / frad)
frad += vrad * dayskip
#ftheta += dftheta
#fphi += dfphi
x, y, z = to_car(frad, ftheta, fphi)
pos.append(
np.array([x, y, z])
) #pos[-1]+np.array([dx,dy,dz]))#pos[-1]+[x*float(i-ind[crs.places[-1]]) for x in di[-1]])
vel.append(vel[-1])
#vel = ?
px.append(pos[-1][0])
py.append(pos[-1][1])
pz.append(pos[-1][2])
dprobe.append(np.sqrt(pos[-1].dot(pos[-1])))
##This also now works!
ISP = ICRF(pos, vel, t=tp, center=0)
#print(ISP.t[ind[m]])
#ICRF positions don't support slicing
#print(ISP.position.au[ind[m]])
#Need to think about viewing - angular size and separation from the Sun
sizes = {p: [None] * len(t) for p in planetsonly} #angular size in arcseconds
angles = {p: [None] * len(t)
for p in planetsonly} #angle in degrees between sun and planet p
mag = {p: [None] * len(t)
for p in planetsonly} #apparent V-band magnitude of planet p
camera = {p: [x[:] for x in [[None] * 3] * len(t)]
for p in planetsonly} #angle in degrees between sun and planet p
#out_of_frame = {p:[None]*len(t) for p in planetsonly} #records size when planet p is more than 90 degrees away from Sun
#in_frame = {p:[None]*len(t) for p in planetsonly} #records size when planet p is less than 90 degrees away from Sun
#alpha = {p:[None]*len(t) for p in planetsonly} #angle in degrees between sun and observer from planet p
def test_subtraction():
p0 = ICRF((10,20,30), (40,50,60))
p1 = ICRF((1,2,3), (4,5,6))
p = p0 - p1
assert tuple(p.position.au) == (9, 18, 27)
assert tuple(p.velocity.au_per_d) == (36, 45, 54)
def make(cls, pos: ICRF) -> "EclipticPosition":
lat, lon, _, latR, lonR, __ = pos.frame_latlon_and_rates(ecliptic_frame)
return EclipticPosition(lat, latR, lon, lonR)
def write_PV_to_file(tle_obj_vec: list[dict],
t0: datetime,
tf: datetime,
timestep: float,
filepath: str = "sats-TLE-example.json") -> None:
import json
from collections import OrderedDict
import numpy as np
from sgp4.api import Satrec, SatrecArray, jday
from skyfield.api import load
from skyfield.sgp4lib import TEME
from skyfield.units import Velocity, Distance
from skyfield.framelib import ecliptic_J2000_frame
from skyfield.positionlib import ICRF
json_posveldata = OrderedDict()
# all TLEs (w/ diff epochs) will be propagated to current time.
epoch_error_flag = False
time_vec = [t0]
t = t0
while t < tf:
t += datetime.timedelta(seconds=timestep)
time_vec.append(t)
years, months, days, hours, minutes, seconds = zip(*[(t.year, t.month,
t.day, t.hour,
t.minute, t.second)
for t in time_vec])
years, months, days, hours, minutes, seconds = np.array(years), np.array(
months), np.array(days), np.array(hours), np.array(minutes), np.array(
seconds)
jds, frs = jday(years, months, days, hours, minutes, seconds)
satrecs_vec = []
for item in tle_obj_vec:
sat_name = item["NORAD_CAT_ID"]
epoch = datetime.datetime.fromisoformat(item["EPOCH"])
if (tf > (epoch + datetime.timedelta(days=5))) or (
tf < (epoch - datetime.timedelta(days=5))):
# raise TypeError(f" Final propagation date {tf} is more than 5 days away from latest TLE epoch ({epoch}), for satellite {sat_name}} ")
epoch_error_flag = True
sat = Satrec.twoline2rv(item["TLE_LINE1"], item["TLE_LINE2"])
satrecs_vec.append(sat)
json_posveldata[sat_name] = {"P": [], "V": []}
satrecs = SatrecArray(satrecs_vec)
errors, rs, vs = satrecs.sgp4(jds, frs) # r,v in TEME frame
ts = load.timescale()
for idxsat, satdata in enumerate(json_posveldata.values()):
for idxtime, (jdi, fri) in enumerate(zip(jds, frs)):
# convert to J2000
ttime = ts.ut1_jd(jdi + fri)
rvicrf = ICRF.from_time_and_frame_vectors(
t=ttime,
frame=TEME,
distance=Distance(km=rs[idxsat][idxtime]),
velocity=Velocity(km_per_s=vs[idxsat][idxtime]))
# rvj2000 = rvicrf.frame_xyz_and_velocity(ecliptic_J2000_frame)
# pos_timestep_j2000, vel_timestep_j2000 = rvj2000[0].m, rvj2000[1].m_per_s
pos_timestep_j2000, vel_timestep_j2000 = rvicrf.position.m, rvicrf.velocity.m_per_s
satdata["P"].append(pos_timestep_j2000.tolist())
satdata["V"].append(vel_timestep_j2000.tolist())
# satdata["P"] = rs[idxsat].tolist() #TEME
# satdata["V"] = vs[idxsat].tolist() #TEME
if errors.any():
print("SGP4 errors found.") # check errror type.
if epoch_error_flag:
print(
f"Warning: Results obtained might be inaccurate. Final propagation date {tf} is more than 5 days away from latest TLE epoch ({epoch}), for satellite {sat_name} "
)
with open(filepath, "w") as file:
json.dump(json_posveldata, file, indent=6)
print(f"PV File written successfully at {filepath}.")
from skyfield.api import Topos, load
from skyfield.api import EarthSatellite
from skyfield.positionlib import ICRF
from skyfield.positionlib import Geometric
from skyfield.positionlib import Barycentric
ts = load.timescale()
thisx = 4085.0136322698854
thisy = -1852.4897691900894
thisz = -4916.7862179899175
vec = ICRF([thisx,thisy,thisz])
vec.t = ts.utc(2020, 3, 18, 3, 36, 35.0)
vecG1 = Geometric([thisx,thisy,thisz])
vecG1.t = ts.utc(2020, 3, 18, 3, 36, 35.0)
satellites = load.tle_file('fullcatalog.txt')
print( 'Loaded', len(satellites), 'satellites')
firsttime = ts.utc(2020, 3, 18, 3, 36, 35.0)
for sat in satellites:
geocentric = sat.apparent(firsttime)
thatx, thaty, thatz = geocentric.position.km
print(geocentric.position.km)
#if (thatx == thisx):
