def is_sun_up_at(t):
"""The function that this returns will expect a single argument that is a
:class:`~skyfield.timelib.Time` and will return ``True`` if the sun is up
or twilight has started, else ``False``."""
t._nutation_angles = iau2000b(t.tt)
# Return `True` if the sun has risen by time `t`.
return topos_at(t).observe(
sun).apparent().altaz()[0].degrees > -degBelowHorizon
def is_planet_transit_at(t):
"""The function that this returns will expect a single argument that is a
:class:`~skyfield.timelib.Time` and will return ``True`` if the moon is up
or twilight has started, else ``False``."""
t._nutation_angles = iau2000b(t.tt)
# Return `True` if the meridian is crossed by time `t`.
position = earth.at(t).observe(planet_name)
ra = position.apparent().radec(epoch='date')[0]
#return t.gast > ra.hours # incorrect
return (t.gast - ra.hours + 12) % 24 - 12 > 0
def moon_phase(t=None):
"""Return the phase of the moon at time `t`. 0 = New, 25 = Fisrt Quarter, 50 = Full, etc."""
if t is None: t = now()
t._nutation_angles = iau2000b(t.tt)
e = earth.at(t)
_, mlon, _ = e.observe(moon).apparent().ecliptic_latlon('date')
_, slon, _ = e.observe(sun).apparent().ecliptic_latlon('date')
# phase = ((mlon.radians - slon.radians) // (tau / 8) % 8).astype(int)
phase = ((mlon.radians - slon.radians) / (tau / 100) % 100)
return round(phase, ROUNDING)
def is_target_up_at(t):
"""Return `True` if the target has risen by time `t`."""
t._nutation_angles = iau2000b(t.tt)
return topos_at(t).observe(
target).apparent().altaz()[0].degrees > -0.8333
def f(t):
length = t.tt.shape[0]
t._nutation_angles = iau2000b(t.tt)
return sat.at(t).is_sunlit(eph)
f.rough_period = 0.001
T0 = time()
t2, y2 = almanac.find_discrete(pass_start, pass_end, f, epsilon=half_second)
print(time() - T0, 'seconds to find moment of entering shadow:')
for ti, yi in zip(t2, y2):
print(' ', ti.utc_jpl(), 'entered sunlight' if yi else 'entered shadow')
one_second = 1.0 / 24.0 / 3600.0
tt = np.arange(pass_start.tt, pass_end.tt, one_second)
T0 = time()
t = ts.tt_jd(tt)
t._nutation_angles = iau2000b(t.tt)
satpos = (sat - topos).at(t)
is_sunlit = satpos.is_sunlit(eph)
DT = time() - T0
print(
DT, 'to compute is_sunlit() for every second of {}-second pass'.format(
len(tt)))
T0 = time()
alt, az, distance = satpos.altaz()
DT = time() - T0
print(DT, 'to re-use the positions to compute altitude and azimuth')
print(__doc__.rstrip())
def is_sun_up_at(t):
"""Return `True` if the sun has risen by time `t`."""
t._nutation_angles = iau2000b(t.tt)
return topos_at(t).observe(
sun).apparent().altaz()[0].degrees > -degrees
def get_iau2000b(time: Time):
return iau2000b(time.tt)
def solar_term_at(t):
"""Return season 0 through 23 at time `t`."""
t._nutation_angles = iau2000b(t.tt)
e = earth.at(t)
_, slon, _ = e.observe(sun).apparent().ecliptic_latlon('date')
return (slon.radians // (tau / 24) % 24).astype(int)
def _phase_degree_at(t):
t._nutation_angles = iau2000b(t.tt)
e = EARTH.at(t)
_, mlon, _ = e.observe(obj).apparent().ecliptic_latlon('date')
_, slon, _ = e.observe(SUN).apparent().ecliptic_latlon('date')
return (mlon.degrees - slon.degrees) % 360
def _observe_at(t):
t._nutation_angles = iau2000b(t.tt)
return topos_at(t).observe(planet).apparent()
de421 = load('de421.bsp')
earth = de421['earth']
ts = load.timescale()
this_sat = EarthSatellite('1 00000U 21 0A 20146.43738583 .00000000 00000-0 00000-0 0 0000',
'2 00000 0.2000 000.0000 0000000 0.0000 000.0000 14.88336848949720', 'Test_600kmAlt', ts)
#100K times between 2022 and 2024
n_steps = 10000
jdrange = np.linspace(2459690.5,2460055.75,n_steps)
utrange = ts.ut1_jd(jdrange)
utrange._nutation_angles = iau2000b(utrange.tt)
#Crab Nebula
target_ra = 83.63308333
target_dec = 22.0145
#My RA is in degrees, hence the division by 15.
target_pos = position_of_radec(target_ra / 15., target_dec)
#Currently not optimized for speed
bool_list = []
t_list = []
for this_ut in tqdm.tqdm(utrange):
this_bool = this_sat.is_target_occulted(this_ut, target_pos, earth)
dist_intersect = this_sat.intersect_line_with_sphere(this_ut, target_pos, earth)
def is_body_up_at(t):
t._nutation_angles = iau2000b(t.tt)
return observer.at(t).observe(target).apparent().altaz()[0].degrees > h
