def main():
ts = load.timescale()
t = ts.tt(2018, 1, 22, 9, 9, 20)
trial_angles = 10, 20, 30, 40 # the error peaks around 20 degrees
trial_elevations = 0, 6000, AU_M
print(__doc__)
for n in range(1, 5):
print('=== {} iterations ==='.format(n))
print('')
for elevation_m in trial_elevations:
for degrees in trial_angles:
top = Topos(latitude_degrees=degrees, longitude_degrees=123,
elevation_m=elevation_m)
xyz_au = top.at(t).position.au
xyz_au = einsum('ij...,j...->i...', t.M, xyz_au)
lat, lon, elev = reverse_terra(xyz_au, t.gast, n)
lat = lat / DEG2RAD
error_mas = 60.0 * 60.0 * 1000.0 * abs(degrees - lat)
print('latitude {} degrees, elevation {} m'
' -> error of {:.2f} mas'
.format(degrees, elevation_m, error_mas))
print('')
print("""\
Given that iterations=3 pushes the maximum error from tens of mas ("mas"
means " milli-arcsecond") down to hundredths of a mas, it is the value
we have chosen as a default. A fourth iteration, if we ever chose to
perform one, pushes the error down to "0.00 mas".
""")
def test_earth_deflection():
# The NOVAS library includes the Earth's gravitational deflection of
# light for both topocentric observers and observers in Earth orbit,
# but shuts this effect off once the object is behind the Earth 20%
# of the way from its limb towards its center. This test determines
# whether Skyfield puts the resulting discontinuity in the same
# place as the NOVAS library does.
#
# For more details see:
# https://github.com/skyfielders/astronomy-notebooks/blob/master/Skyfield-Notes/Fixing-earth-deflection.ipynb
t = load.timescale(delta_t=0.0)
t = t.tt(2016, 7, 2, arange(10.5628, 10.5639, 0.0002))
planets = load('de405.bsp')
earth = planets['earth']
mars = planets['mars']
lowell = earth + Topos(latitude_degrees=35.2029, longitude_degrees=-111.6646)
ra, dec, distance = lowell.at(t).observe(mars).apparent().radec()
h = ra.hours
hprime = diff(h)
assert hprime[0] > 1.8e-8
assert hprime[1] > 1.8e-8
assert hprime[2] < 1.3e-8 # moment when nadir angle crosses 0.8
assert hprime[3] > 1.8e-8
assert hprime[4] > 1.8e-8
def compute_flight_time(planets, start_name, destination_name, g):
start = planets[start_name + ' barycenter']
destination = planets[destination_name + ' barycenter']
ts = load.timescale()
t = ts.now()
astrometric = start.at(t).observe(destination)
distance = astrometric.distance().km
acceleration = acceleration_g_to_km_sec_sqr(g)
time_of_flight = flip_and_burn(acceleration, distance)
return time_of_flight
def get_next_pass(satellite, satellite_name):
# Create a time vector of 24 hours
ts = load.timescale()
current = datetime.datetime.now()
minutes = range(current.minute, 60 * 24 + current.minute)
t = ts.utc(current.year, current.month, current.day, current.hour, \
minutes)
orbit = (satellite - GROUND_STATION).at(t)
alt, az, distance = orbit.altaz()
above_horizon = alt.degrees > 0
boundaries, = np.diff(above_horizon).nonzero()
passes = boundaries.reshape(len(boundaries) // 2, 2)
if len(passes) > 0:
return passes[0]
else:
print("Error, no passes found for {}".format(satellite_name))
sys.exit(2)
def calc_radec_w_proper_motion(ra, de, pmra, pmde, epoch=2018.):
planets = load('/Users/gks/Dropbox/mypylib/notebooks/GIT/HETobs/de421.bsp')
ts = load.timescale()
earth = planets['earth']
t = ts.utc(epoch)
t_2000 = ts.utc(2000)
ra_ang = Angle(degrees=ra)
de_ang = Angle(degrees=de)
star_obj = Star(ra=ra_ang,
dec=de_ang,
ra_mas_per_year=pmra,
dec_mas_per_year=pmde)
astrometric = earth.at(t).observe(star_obj)
ra_out, dec_out, dist_out = astrometric.radec()
ra_new = ra_out.to(u.degree).value
de_new = dec_out.to(u.degree).value
print("Old:", ra, de)
print("New:", ra_new, de_new)
return ra_new, de_new
def plotear_planetas(self):
planetas = load('de421.bsp') #Cargando planetas
self.earth, venus, sun, mercury, neptune, mars, saturn, jupyter, uranus, moon = planetas[
'earth'], planetas['venus'], planetas['sun'], planetas[
1], planetas[8], planetas['mars'], planetas[6], planetas[
5], planetas[7], planetas['moon']
ts = load.timescale()
t = ts.utc(self.fecha_hora.replace(tzinfo=utc))
self.graficar_planeta(venus, t, 'Venus')
self.graficar_planeta(mercury, t, 'Mercurio')
self.graficar_planeta(mars, t, 'Marte')
self.graficar_planeta(saturn, t, 'Saturno')
self.graficar_planeta(jupyter, t, 'Jupiter')
self.graficar_planeta(neptune, t, 'Neptuno')
self.graficar_planeta(sun, t, 'Sol')
self.graficar_planeta(moon, t, 'Luna')
self.graficar_planeta(uranus, t, 'Urano')
def greatest_elevation_schedule(ordered_events, location):
pass_T = 120. # length of minimum pass in seconds
exposure_T = 20. # length of exposure
buffer_T = 40. + exposure_T # time between exposures
ts = load.timescale()
site = wgs84.latlon(location[0], location[1], elevation_m=0)
ccd_schedule = []
jSec = 1.0 / 24 / 60 / 60 # second in julian time
for event in ordered_events:
elevations = list()
for tdx, t in enumerate(np.linspace(event[1], event[2], 100)):
difference = event[0] - site
elevations.append(difference.at(ts.tt_jd(tdx)).elevation)
event.append(event[1]
+ (event[2]-event[1])/100*elevations.index(max(elevations)))
def main():
print('Skyfield version: {0}'.format(skyfield.__version__))
print('jplephem version: {0}'.format(version_of('jplephem')))
print('sgp4 version: {0}'.format(version_of('sgp4')))
ts = load.timescale()
fmt = '%Y-%m-%d'
final_leap = (ts._leap_tai[-1] - 1) / (24 * 60 * 60)
print('Built-in leap seconds table ends with leap second at: {0}'.format(
ts.tai_jd(final_leap).utc_strftime()))
arrays = load_bundled_npy('iers.npz')
daily_tt = arrays['tt_jd_minus_arange']
daily_tt += np.arange(len(daily_tt))
start = ts.tt_jd(daily_tt[0])
end = ts.tt_jd(daily_tt[-1])
print('Built-in ∆T table from finals2000A.all covers: {0} to {1}'.format(
start.utc_strftime(fmt), end.utc_strftime(fmt)))
def main():
## get the global parameters
global wcs, imgSize, refUTC, imgScale, mwa, ts, line1, line2, line3
hdu = fits.open(
str(args.obs) + "-" + str(args.midName) + "-1-0000-dirty.fits")
wcs = WCS(hdu[0].header, naxis=2)
imgSize = hdu[0].header["NAXIS1"]
imgScale = np.abs(hdu[0].header["CDELT2"])
refUTC = datetime.strptime(hdu[0].header["DATE-OBS"],
'%Y-%m-%dT%H:%M:%S.%f')
## get the relevant tle for the satellite
line1, line2, line3 = obtainTLE(args.noradid)
if args.debug:
print("line1 {0}\nline2 {1}\nline3 {2}".format(line1, line2, line3))
mwa = Topos("26.701276778 S", "116.670846137 E", elevation_m=377.827)
ts = load.timescale()
intrack_offset_array = np.linspace(-10, 10, 10)
offtrack_offset_array = np.linspace(-0.5, 0.5, 10)
all_combinations = [(a, b) for a in intrack_offset_array
for b in offtrack_offset_array]
waterfall = np.zeros((10, 10, args.channels))
for f in tqdm(range(args.channels)):
if args.debug:
print("working on channel {}".format(f))
global utc_array, cube
utc_array, cube = getCube(f)
with multiprocessing.Pool(processes=28) as pool:
results = pool.starmap(worker, all_combinations)
results = np.array(results)
waterfall[:, :, f] = results.reshape((10, 10))
np.save(
str(args.noradid) + "-" + str(args.obs) + "waterfall.npy", waterfall)
def ccd_schedule(schedule, location):
"""
Creates a schedule for use with and external
Parameters:
schedule:
location:
Returns:
"""
# user inputs
pass_T = 120. # length of minimum pass in seconds
exposure_T = 20. # length of exposure
buffer_T = 40. + exposure_T # time between passes
# predefinition
ts = load.timescale()
site = wgs84.latlon(float(location[0]), float(location[1]))
ccd_schedule = []
jSec = 1.0 / 24 / 60 / 60 # second in julian time
# add first event, assuming first event is long enough
event = schedule[0]
difference = event[0] - site
ccd_schedule.append([event[0], event[1], event[1] + buffer_T * jSec])
ccd_schedule[0].extend([difference.at(ts.tt_jd(ccd_schedule[0][1]
+ exposure_T / 2. * jSec)),
difference.at(ts.tt_jd(ccd_schedule[0][2]
+ exposure_T / 2. * jSec))])
for event in schedule[1:]:
if event[1] - buffer_T * jSec > ccd_schedule[-1][2] \
and event[2] > ccd_schedule[-1][2] + (buffer_T + pass_T) * jSec:
difference = event[0] - site
ccd_schedule.append([event[0], max(ccd_schedule[-1][2]
+ buffer_T*jSec, event[1])])
ccd_schedule[-1].append(ccd_schedule[-1][1] + buffer_T * jSec)
ccd_schedule[-1].extend([difference.at(ts.tt_jd(ccd_schedule[-1][1]
+ exposure_T / 2.*jSec)),
difference.at(ts.tt_jd(ccd_schedule[-1][2]
+ exposure_T / 2.*jSec))])
return ccd_schedule
def run():
rospy.init_node('sun_seeker_node', anonymous=True)
rospy.Subscriber('/clock', Clock, sim_time_callback)
pub = rospy.Publisher('/sun_seeker/vector', Vector3, queue_size=1)
rate = rospy.Rate(0.1)
eph = load('de421.bsp')
sun = eph['sun']
moon = eph['moon']
path = os.path.realpath(__file__)
pc = PlanetaryConstants()
pc.read_text(load('moon_080317.tf'))
pc.read_text(load('pck00008.tpc'))
pc.read_binary(load('moon_pa_de421_1900-2050.bpc'))
frame = pc.build_frame_named('MOON_ME_DE421')
place = moon + pc.build_latlon_degrees(frame, -86.79430, -21.18640)
sun_angle_msg = Vector3()
while not rospy.is_shutdown():
dt = datetime.fromtimestamp(sim_time)
dt_utc = dt.replace(tzinfo=pytz.UTC)
ts = load.timescale()
t = ts.from_datetime(dt_utc)
sunpos = place.at(t).observe(sun).apparent()
alt, az, distance = sunpos.altaz()
sun_angle_msg.x = 0.0
sun_angle_msg.y = alt.degrees
sun_angle_msg.z = az.degrees
if rospy.get_time() - last_msg_time < msg_timeout:
rospy.loginfo('Publishing vector: x = {0:.3f}, y = {1:.3f}, z = {2:.3f}'.format(sun_angle_msg.x, sun_angle_msg.y, sun_angle_msg.z))
pub.publish(sun_angle_msg)
else:
rospy.logwarn('Timeout {0:.1f} seconds: Is /clock publishing?'.format(msg_timeout))
rate.sleep()
def hour_angle(self, object_ra: float, object_dec: float, date=None):
"""
Converts the provided right ascension (RA) of an object to its corresponding hour angle (HA), based on the
provided date.
Args:
date: Desired date for the calculation of the hour angle
object_ra (float): The right ascension of the object in J2000
object_dec (float): Object's declination in J2000
Todo:
Check the reason that the the values for the HA differ by almost 2 minutes from the real ones
Todo:
Also add a solid documentation for the whole file, explaining in detail the parsed arguments
Todo:
Update the docstring of this function because there is a major change.
Returns:
float: Calculated hour angle
"""
if date is None:
date = self.current_time()
else:
if len(date) == 3:
day = int(date[2])
hour = (date[2] - day) * 24
minute = (hour - int(hour)) * 60
second = int(minute - int(minute)) * 60
date = (date[0], date[1], day, int(hour), int(minute), second)
object_coordinates = SkyCoord(ra=str(object_ra), dec=str(object_dec), unit='deg')
equinox_time = Time(datetime.datetime(*date), scale='utc', location=self.location, format='datetime')
ra_jnow = object_coordinates.transform_to(FK5(equinox=equinox_time)).ra
# Get the local sidereal time
time_scale = load.timescale()
utc_time = time_scale.utc(*date)
local_sidereal_time = utc_time.gast * 15 + self.location.lon.degree
return round(local_sidereal_time - ra_jnow.degree, 6) # Return the calculated hour angle
def sun_earth_distance(date):
"""
Input:
- UTC datetime object
Output:
- Sun-Earth distance (meters)
"""
planets = load('de421.bsp')
earth, sun = planets['earth'], planets['sun']
ts = load.timescale()
t = ts.utc(date.replace(tzinfo=utc))
astrometric = earth.at(t).observe(sun)
ra, dec, distance = astrometric.radec()
return distance.m
def _convert_radec_to_altaz(ra, dec, lon, lat, height, time):
"""Convert a single position.
This is done for easy code sharing with other tools.
Skyfield does support arrays of positions.
"""
radec = Star(ra=Angle(degrees=ra), dec=Angle(degrees=dec))
earth = load(EPHEMERIS)['earth']
location = earth + Topos(longitude_degrees=lon,
latitude_degrees=lat,
elevation_m=height * 1000.0)
ts = load.timescale()
obstime = ts.from_astropy(Time(time, scale='utc'))
alt, az, _ = location.at(obstime).observe(radec).apparent().altaz(pressure_mbar=0)
return dict(az=az.degrees, alt=alt.degrees)
def generate_report(self):
# the tricky bits to get look angles for a list of times
ts = load.timescale(builtin=True)
# get rid of the milliseconds in there
truth = ts.now().utc
now_ish = ts.utc(truth[0],truth[1],truth[2],truth[3],truth[4],truth[5])
now = now_ish.tt
# make an arry with times incremented by really close to 30 sec
# this looks weird since it is terrestrial time floating point
run_time = arange(now, now + .5, .000347222)
# feed that array to the time function as julian days
t = ts.tt(jd=run_time)
# spit out the positon and vector of our location
astrometric = self.ant.at(t).observe(self.name).apparent()
# convert this to alt and az lists
alt, az, distance = astrometric.altaz()
t_list = t.utc_strftime('%Y:%m:%d:%H:%M:%S')
alt_list = alt.degrees.tolist()
az_list = az.degrees.tolist()
self.report = []
self.rise_time = None
self.fade_time = None
for idx,item in enumerate(t_list):
if alt_list[idx] < 10.0:
continue
else:
if self.rise_time is None:
self.rise_time = t_list[idx]
self.fade_time = t_list[idx]
az_out = "{:.4f}".format(az_list[idx])
alt_out = "{:.4f}".format(alt_list[idx])
output = t_list[idx]+", "+az_out+", "+alt_out+"\n"
self.report.append(output)
def get_servo(lat, lng, sat_name, timestamp):
ts = load.timescale()
lines = get_sat(sat_name)
line1 = lines[0]
line2 = lines[1]
current_time = timestamp
my_position = Topos(lat, lng)
satellite = EarthSatellite(line1, line2, sat_name, ts)
difference = satellite - my_position
data = ""
for i in range(720):
dt_object = datetime.utcfromtimestamp(current_time)
dt_object = dt_object.replace(tzinfo=utc)
t = ts.utc(dt_object)
topocentric = difference.at(t)
alt, az, distance = topocentric.altaz()
alt_d = alt.degrees
az_d = az.degrees
if (az_d > 180):
alt_d = flit_alt(alt_d)
az_d = az_d - 180
if (az_d < 0):
alt_d = flit_alt(alt_d)
az_d = 180 + az_d
# print(current_time,az_d,alt_d)
data += str(current_time) + ', ' + str(
translate(az_d, 0, 180, 2457, 7372)) + ", " + str(
translate(alt_d, 0, 180, 2457, 7372)) + '\n'
current_time += 1
return data
def search(self, sat, lat, long, timeStart, timeEnd, tolerance):
"""
Returns the time for which a satellite is over the given coordinates within the time range given
:param satellite sat: The satellite of interest
:param float lat: The latitude of the search point
:param float lon: The longitude of the search point
:param datetime timeStart: The beginning of the time range to search through
:param datetime timeEnd: The end of the time range to search through
:param float tolerance: How close a satellite needs to the point (in km)
:returns: The time at which the satellite is over the given coordinates. Returns None if not found
:rtype: datetime
"""
self.satellite = self.satellites[sat.name]
# Calculate orbital period
n = float(sat.meanMotion)
mu = 398600; # km^3/s^2
a = mu**(1/3) / (2*n*pi/86400)**(2/3)
T = 2*pi*(a**3/mu)**(1/2)
# Determine dt
ts = load.timescale()
dt = timedelta(seconds = T/100)
# Search for time
t = timeStart
while t <= timeEnd:
currentTime = ts.utc(t.year, t.month, t.day, t.hour, t.minute,
t.second)
geocentric = self.satellite.at(currentTime)
subpoint = geocentric.subpoint()
currentLat = subpoint.latitude.degrees
currentLong = subpoint.longitude.degrees
if(haversine((lat, long), (currentLat, currentLong)) < tolerance):
return t
t = t + dt
# If nothing found return None
return None
def test_radec_and_altaz_angles_and_rates():
# HORIZONS test data in Skyfield repository: authorities/radec-altaz-rates
ts = load.timescale()
t = ts.utc(2021, 2, 3)
top = wgs84.latlon(35.1844866, 248.347300, elevation_m=2106.9128)
planets = load('de421.bsp')
a = (planets['earth'] + top).at(t).observe(planets['mars']).apparent()
# First, verify RA and declination.
frame = framelib.true_equator_and_equinox_of_date
dec, ra, distance, dec_rate, ra_rate, range_rate = (
a.frame_latlon_and_rates(frame))
arcseconds = 3600.0
assert abs((ra.degrees - 40.75836) * arcseconds) < 0.04
assert abs((dec.degrees - 17.16791) * arcseconds) < 0.005
assert abs(distance.m - 1.21164331503552 * AU_M) < 120.0
# Verify RA and declination rates of change.
assert round(dec_rate.arcseconds.per_hour, 5) == 25.61352
assert round(ra_rate.arcseconds.per_hour * cos(dec.radians),
4) == round(75.15571, 4) # TODO: get last digit to agree?
assert abs(range_rate.km_per_s - 16.7926932) < 2e-5
# Verify altitude and azimuth.
frame = top
alt, az, distance, alt_rate, az_rate, range_rate = (
a.frame_latlon_and_rates(frame))
assert round(alt.degrees, 4) == 65.2758
assert round(az.degrees, 4) == 131.8839
assert abs(distance.m - 1.21164331503552 * AU_M) < 120.0
# Verify altitude and azimuth rates of change.
assert abs(range_rate.km_per_s - 16.7926932) < 2e-5
assert round(alt_rate.arcseconds.per_minute, 2) == 548.66
assert round(az_rate.arcseconds.per_minute * cos(alt.radians), 2) == 663.55
def __init__(self):
self.gps = load.tle_file("https://celestrak.com/NORAD/elements/gps-ops.txt")
self.galileo = load.tle_file("https://celestrak.com/NORAD/elements/galileo.txt")
self.glonass = load.tle_file("https://celestrak.com/NORAD/elements/glo-ops.txt")
self.beidou = load.tle_file("https://celestrak.com/NORAD/elements/beidou.txt")
self.allsat = self.gps+self.galileo+self.glonass+self.beidou
print('Loaded', len(self.allsat), 'satellites')
# create dict where we can fetch a satellite using its name as key
self.sats_by_name = {sat.name: sat for sat in self.allsat}
# Define observatory for az,el calculation
self.obs = Topos('57.393109 N', '11.917798 E') # OSO25m
# Define timerange, https://rhodesmill.org/skyfield/time.html
self.ts = load.timescale()
self.tgps = False
self.tgalileo = False
self.tglonass = False
self.tbeidou = False
#self.sat2plot = self.gps+self.galileo
self.sat2plot = []
# Plot the data, awaiting key-press events
self.plot()
def get_range_velocity(sat_name: str, obs_lat: float, obs_lon: float,
time: datetime) -> typing.List[float]:
ts = load.timescale()
if isinstance(time, str):
time = parse(time)
time = time.replace(tzinfo=utc)
time = ts.utc(time) if time is not None else ts.now()
observer = Topos(obs_lat, obs_lon)
stations_url = "http://celestrak.com/NORAD/elements/stations.txt"
satellites = load.tle(stations_url)
sat = satellites[sat_name]
relative_position = (sat - observer).at(time)
# sat_velocity = sat.at(tnow).velocity.km_per_s
range_velocity = relative_position.velocity.km_per_s
return range_velocity
def getSatMWA(line1, line2, line3):
"""
creates a satellite object and observer object
Paramters
---------
line1 : tle line 1
line2 : tle line 2
line3 : tle line 3
Returns
-------
satellite : the sat object
mwa : the observer object
ts : the time object
"""
ts = load.timescale(builtin=True)
satellite = EarthSatellite(line2, line3, line1, ts)
mwa = Topos("26.701276778 S", "116.670846137 E", elevation_m= 377.827)
return satellite, mwa, ts
def test_using_elevation_to_locate_center_of_moon():
# Test the `elevation_m` parameter by using it to offset a Moon
# surface location back to the Moon's center.
ts = load.timescale()
t = ts.utc(2020, 4, 23)
eph = load('de421.bsp')
a1 = eph['moon'].at(t)
pc = PlanetaryConstants()
pc.read_text(load('moon_080317.tf'))
pc.read_text(load('pck00008.tpc'))
pc.read_binary(load('moon_pa_de421_1900-2050.bpc'))
frame = pc.build_frame_named('MOON_ME_DE421')
place = pc.build_latlon_degrees(frame, 26.3, 313.2, -1737400)
a2 = (eph['moon'] + place).at(t)
mm = 1e-3
assert max(abs(a1.position.m - a2.position.m)) < mm
def get_adcs_vectors(time_data, tle_data):
sun = JPL_EPH['sun']
earth = JPL_EPH['earth']
ts = load.timescale()
label="Satellite"
satellite = EarthSatellite(tle_data["line_1"], tle_data["line_2"], label, ts)
time_instant = ts.utc(
time_data["year"],
time_data["month"],
time_data["day"],
time_data["hour"],
time_data["min"],
time_data["sec"],
)
tru_pos = earth + satellite
sun_vector1 = tru_pos.at(time_instant).observe(sun).apparent().position.km
sun_vector2 = satellite.at(time_instant).position.km
# sun_vector = satellite.at(time_instant).observe(earth).apparent()
# print(tru_pos.at(time_instant).position.km)
# print(earth.at(time_instant).position.km)
return [sun_vector1 - sun_vector2]
def test_minor_planet():
text = (b'00001 3.4 0.15 K205V 162.68631 73.73161 80.28698'
b' 10.58862 0.0775571 0.21406009 2.7676569 0 MPO492748'
b' 6751 115 1801-2019 0.60 M-v 30h Williams 0000 '
b'(1) Ceres 20190915\n')
ts = load.timescale()
t = ts.utc(2020, 6, 17)
eph = load('de421.bsp')
df = mpc.load_mpcorb_dataframe(BytesIO(text))
row = df.iloc[0]
assert row.designation_packed == '00001'
assert row.designation == '(1) Ceres'
ceres = mpc.mpcorb_orbit(row, ts, GM_SUN)
ra, dec, distance = eph['earth'].at(t).observe(eph['sun'] + ceres).radec()
assert ceres.target == '(1) Ceres'
assert abs(ra.hours - 23.1437) < 0.00005
assert abs(dec.degrees - -17.323) < 0.0005
def hour_angle_to_ra(self, object_ha: float, object_dec: float, date=None):
"""
Convert the provided object's hour angle to its corresponding right ascension. This method assumes that ephem is
properly calibrated. Also the date is assumed to be now.
Todo:
Check what happens in every case and if the conversion of degrees is needed
Args:
object_ha (float): Hour angle of the desired object
object_dec (float): Declination of the object
date (tuple): The desired date
Returns:
The current right ascension of the object in J2000
"""
# Get the local sidereal time
if date is None:
date = self.current_time() # Get the current time and date as needed
else:
if len(date) == 3:
day = int(date[2])
hour = (date[2] - day)*24
minute = (hour - int(hour))*60
second = int(minute - int(minute))*60
date = (date[0], date[1], day, int(hour), int(minute), second)
# Calculate the desired right ascension
time_scale = load.timescale()
utc_time = time_scale.utc(*date)
local_sidereal_time = utc_time.gast * 15 + self.location.lon.degree
calculated_ra = local_sidereal_time - object_ha # Calculate the right ascension in JNOW
# Calculate the right ascension of the provided object in J2000
equinox_time = Time(datetime.datetime(*date), scale='utc', location=self.location, format='datetime')
object_coordinates = SkyCoord(ra=str(calculated_ra), dec=str(object_dec), unit='deg',
frame=FK5, equinox=equinox_time)
ra_j2000 = object_coordinates.transform_to(FK5(equinox='J2000.0')).ra
return round(ra_j2000.degree, 6)
def compare_obj(planets, code, year, month, day, hour=0, minute=0, second=0):
'''
compare position between jpl query and skyfield computation
parameters:
----------
code : 1,2,3,4,5,6,7,8,9,10,199,299,399,301
year: int,
month: int,
day: int,
hour: int default 0,
minute: int default 0,
second float default 0,
'''
# print(code)
ts = load.timescale()
t = ts.utc(year, month, day, hour, minute, second)
objname = planets.names()[code][0]
# print(objname)
obj = planets[objname]
icrf_sf = obj.at(t)
# print(icrf_sf.position)
icrf_sf_np = icrf_sf.position.km
time = Time(t.utc_iso())
times = time.tt+np.linspace(0, 1, 2)*u.s
objquery = Horizons(id=str(code), id_type='majorbody', location='@0',
epochs={'start': times.value[0], 'stop': times.value[1], 'step': '1'})
icrf_jpl = objquery.vectors(refplane='earth')
icrf_jpl['x'].convert_unit_to('km')
icrf_jpl['y'].convert_unit_to('km')
icrf_jpl['z'].convert_unit_to('km')
icrf_jpl_np = np.array(
[icrf_jpl['x'][0], icrf_jpl['y'][0], icrf_jpl['z'][0]])
print(objname + ' icrf_sf_np in km', icrf_sf_np)
print(objname + ' icrf_jpl_np in km', icrf_jpl_np)
print(objname + ' icrf_sf_np-icrf_jpl_np in km', icrf_sf_np-icrf_jpl_np)
print()
def test_against_horizons():
# See the following files in the Skyfield repository:
#
# horizons/ceres-orbital-elements
# horizons/ceres-position
ts = load.timescale(builtin=True)
t = ts.tdb_jd(2458886.500000000)
a = 2.768873850275102E+00 # A
e = 7.705857791518426E-02 # EC
p_au = a * (1 - e**2) # Wikipedia
k = KeplerOrbit.from_mean_anomaly(
p=Distance(au=p_au), # see above
e=e,
i=Angle(degrees=2.718528770987308E+01),
Om=Angle(degrees=2.336112629072238E+01),
w=Angle(degrees=1.328964361683606E+02),
M=Angle(degrees=1.382501360489816E+02),
epoch=t, #?
mu_km_s=None,
mu_au_d=2.9591220828559093E-04,
center=None,
target=None,
center_name=None,
target_name=None,
)
r, v = k._at(t)[:2]
sun_au = [
-0.004105894975783999,
0.006739680703224941,
0.002956344702049446,
]
horizons_au = [
1.334875927366032E+00,
-2.239607658161781E+00,
-1.328895183461897E+00,
]
assert max(abs(r + sun_au - horizons_au)) < 2e-15
def sat_separations(params):
'''
Separation between a source and set of satellites.
Parameters
----------
params: list
[[source_ra, source_dec], date]
source_ra: float
Right Ascension of source in radians.
source_dec: float
Declination of source in radians.
date: datetime
Date and time of observation.
Returns
-------
separations: array
Angular separation between each satellite and the source in degrees.
'''
source, t = params
source_ra, source_dec = source
satellites = get_sat_tles()
ts = load.timescale()
tt = ts.utc(*[int(x) for x in t.strftime('%Y %m %d %H %M %S').split()])
mkat = Topos('30.7130 S', '21.4430 E')
separations = np.zeros((len(satellites.items())))
for j, sat in enumerate(satellites.items()):
sat_ra, sat_dec = [(sat[1]-mkat).at(tt).radec(ts.J2000)[i].radians for i in range(2)]
separations[j] = np.rad2deg(angular_separation(sat_ra, sat_dec, [source_ra, source_dec]))
return separations
def readTLE(fileName='./india_tle.dat'):
# tle referesh days
refresh_days = 14
# current date and time
ts = load.timescale(builtin=True)
t = ts.now()
days = 1
if not os.path.exists(fileName):
# call create local tle function
print("Creating new tle file")
dict = getISROSatelliteList()
saveTLE(dict, fileName)
# load the new one
satellites = load.tle(fileName)
else:
# load the local file
satellites = load.tle(fileName)
# get the first in the dictionary
sat_id = list(satellites.keys())[0]
satellite = satellites[sat_id]
days = t - satellite.epoch
# if older than refresh_days create new local tle and load new one
if abs(days) > refresh_days:
# call create local tle function
print("Creating new tle file")
dict = getISROSatelliteList()
saveTLE(dict, fileName)
# load the new one
satellites = load.tle(fileName)
# sats dictionary for easy search
sats = {}
for item in [satellites]:
names = [key for key in item.keys()]
for satname in names:
sat = item[satname]
satid = sat.model.satnum
sats[satid] = sat
sats[satname] = sat
# return dictionary
return sats
def readTLE(fileName='./india_tle.dat'):
# tle referesh days
refresh_days = 14
# current date and time
ts = load.timescale(builtin=True)
t = ts.now()
days = 1
old_date = 0
# call create local tle function
print("Creating new tle file")
dict = getISROSatelliteList()
saveTLE(dict, fileName)
# load the new one
satellites = load.tle(fileName)
if abs(days) > refresh_days:
# call create local tle function
print("Creating new tle file")
# backup old tle
backupFilename = Path(fileName).stem + old_date + '.dat'
os.rename(fileName, backupFilename)
# get the new one
dict = getISROSatelliteList()
saveTLE(dict, fileName)
# load the new one
satellites = load.tle(fileName)
# sats dictionary for easy search
sats = {}
for item in [satellites]:
names = [key for key in item.keys()]
for satname in names:
sat = item[satname]
satid = sat.model.satnum
sats[satid] = sat
sats[satname] = sat
# return dictionary
return sats
def hip_position(hip_nr, temperature=15, pressure=1005):
""" Returns uncorrected and refraction corrected apparent positions of stars in the Hipparcos catalogue.
Position is specified to Waltz observer.
"""
#Load list of planets and specify to earth to get obersver, then specify to location of Waltz
planets = load('de421.bsp')
earth = planets['earth']
waltz = earth + Topos(
'49.3978620896919 N', '8.724700212478638 E', elevation_m=562.0)
#Load current time.
ts = load.timescale()
t = ts.now()
#t=t.utc #Convert
#Load star catalogue coordinates from hipparcos.py module
star = hipparcos.get(hip_nr)
#Compute astrometric and apparent coordinates for Waltz at time t
astrometric = waltz.at(t).observe(star)
apparent = astrometric.apparent()
#Change to alt, az coordinates to compute refraction correction, then change back again
#Change Temp and pressure
alt, az, distancealt = apparent.altaz(temperature_C=temperature,
pressure_mbar=pressure)
corrected = apparent.from_altaz(alt=alt, az=az)
#RA,DEC,Dist of refraction corrected positions
ra_calc, dec_calc, distance = corrected.radec()
#RA,DEC,Dist of refraction uncorrected positions
ra_calc_without_refraction, dec_calc_without_refraction, distance = apparent.radec(
epoch='date')
return [
ra_calc, dec_calc, ra_calc_without_refraction,
dec_calc_without_refraction
]
def _get_times(self, now: datetime) -> (datetime, datetime):
midnight = now.replace(hour=0, minute=0, second=0, microsecond=0)
next_midnight = midnight + timedelta(days=1)
ts = load.timescale()
t0 = ts.from_datetime(midnight)
t1 = ts.from_datetime(next_midnight)
eph = load_file(config['DE421_PATH'])
bluffton = wgs84.latlon(config['COORDINATES']['N'] * N, config['COORDINATES']['E'] * E)
f = almanac.dark_twilight_day(eph, bluffton)
times, events = almanac.find_discrete(t0, t1, f)
result = []
previous_e = None
for t, e in zip(times, events):
if e == 4:
result.append(t.astimezone(self.zone))
if previous_e == 4:
result.append(t.astimezone(self.zone))
previous_e = e
return result[0], result[1]
def rise_and_set_time(self, satellite):
"""
Accepts a satellite, returns the next rise and set time for that satellite
as a tuple of datetimes
"""
# create skyfield latlon
loc = wgs84.latlon(self.lat, self.lon)
# create timescale
ts = load.timescale()
t0, t1 = ts.from_datetimes(self.time_window(1))
# get events where satellite reaches altitude at location in time window
times, _ = satellite.find_events(
loc, t0, t1, altitude_degrees=self.altitude_degrees)
# get rise and sent time for first event
rise_time = times[0].utc_datetime()
set_time = times[2].utc_datetime()
return (rise_time, set_time)
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 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 position and velocity at date t center=499 target=399>"
geocentric = Geocentric([0,0,0])
assert geocentric.center == 399
def __init__(self, lg=None,obs=None,refraction_method=None):
#
self.lg=lg
self.name='SF Skyfield'
self.obs_astropy=obs
self.refraction_method=refraction_method
longitude,latitude,height=self.obs_astropy.to_geodetic()
# positive values are used for eastern longitudes
# ToDo
# print(type(height))
# print(str(height))
# 3236.9999999999477 m
# print(height.meter)
# AttributeError: 'Quantity' object has no 'meter' member
elevation=float(str(height).replace('m','').replace('meter',''))
earth = planets['earth']
# N +, E + hurray
self.obs=earth.topos(
latitude_degrees=latitude.degree,
longitude_degrees=longitude.degree,
elevation_m=elevation,
)
self.ts=load.timescale()
def archived_tle():
"""
Return a list of HST TLEs from space-track
https://www.space-track.org/basicspacedata/query/class/tle/EPOCH/2015-01-01--2016-12-31/NORAD_CAT_ID/20580/orderby/TLE_LINE1%20ASC/format/tle
HST_TLE.txt:
https://www.space-track.org/basicspacedata/query/class/tle/EPOCH/2009-08-01--2016-12-31/NORAD_CAT_ID/20580/orderby/TLE_LINE1%20ASC/format/tle
"""
from skyfield.api import load
from skyfield.constants import AU_KM
import astropy.time
ts = load.timescale()
eph = load('de421.bsp')
earth = eph['earth']
#sat = earth.satellite('\n'.join(lines))
#lines = open('2015-16_TLEs.txt').readlines()
#lines = open('HST_TLE.txt').readlines()
lines = open('HST_TLE_WFC3.txt').readlines()
lines = [line.strip() for line in lines]
N = len(lines)//2
times = []
strings = []
for i in range(N):
print(i,N)
tle_str = 'HST\n'+'\n'.join(lines[i*2:i*2+2])
sat = earth.satellite(tle_str)
t0 = astropy.time.Time(sat.epoch.utc_datetime())
times.append(t0.mjd)
strings.append(tle_str)
return np.array(times), np.array(strings)
def test_positions_skyfield():
"""
Test positions against those generated by skyfield.
"""
t = Time('1980-03-25 00:00')
location = None
# skyfield ephemeris
planets = load('de421.bsp')
ts = load.timescale()
mercury, jupiter, moon = planets['mercury'], planets['jupiter barycenter'], planets['moon']
earth = planets['earth']
skyfield_t = ts.from_astropy(t)
if location is not None:
earth = earth.topos(latitude_degrees=location.latitude.to(u.deg).value,
longitude_degrees=location.longitude.to(u.deg).value,
elevation_m=location.height.to(u.m).value)
skyfield_mercury = earth.at(skyfield_t).observe(mercury).apparent()
skyfield_jupiter = earth.at(skyfield_t).observe(jupiter).apparent()
skyfield_moon = earth.at(skyfield_t).observe(moon).apparent()
if location is not None:
obsgeoloc, obsgeovel = location.get_gcrs_posvel(t)
frame = GCRS(obstime=t, obsgeoloc=obsgeoloc, obsgeovel=obsgeovel)
else:
frame = GCRS(obstime=t)
ra, dec, dist = skyfield_mercury.radec(epoch='date')
skyfield_mercury = SkyCoord(ra.to(u.deg), dec.to(u.deg), distance=dist.to(u.km),
frame=frame)
ra, dec, dist = skyfield_jupiter.radec(epoch='date')
skyfield_jupiter = SkyCoord(ra.to(u.deg), dec.to(u.deg), distance=dist.to(u.km),
frame=frame)
ra, dec, dist = skyfield_moon.radec(epoch='date')
skyfield_moon = SkyCoord(ra.to(u.deg), dec.to(u.deg), distance=dist.to(u.km),
frame=frame)
moon_astropy = get_moon(t, location)
mercury_astropy = get_body(t, 'mercury', location)
jupiter_astropy = get_body(t, 'jupiter', location)
# convert to true equator and equinox
jupiter_astropy = _apparent_position_in_true_coordinates(jupiter_astropy)
mercury_astropy = _apparent_position_in_true_coordinates(mercury_astropy)
moon_astropy = _apparent_position_in_true_coordinates(moon_astropy)
assert (moon_astropy.separation(skyfield_moon) <
skyfield_angular_separation_tolerance)
assert (moon_astropy.separation_3d(skyfield_moon) < skyfield_separation_tolerance)
assert (jupiter_astropy.separation(skyfield_jupiter) <
skyfield_angular_separation_tolerance)
assert (jupiter_astropy.separation_3d(skyfield_jupiter) <
skyfield_separation_tolerance)
assert (mercury_astropy.separation(skyfield_mercury) <
skyfield_angular_separation_tolerance)
assert (mercury_astropy.separation_3d(skyfield_mercury) <
skyfield_separation_tolerance)
def __init__(self, observer, time_list):
self.earth = self._createearth()
self.ts = load.timescale()
self.time = self._createdatearray(time_list)
self.obs = self._createobs(observer)
def predictStorms(startdate, predictdays, includeonlyiorelatedFlag, calcinterval, modeflag):
global ts, iterDateUTCtime, th, L3, U1, modeset, JupiterRise, JupiterSet, SunRise, SunSet, includeonlyiorelated, predList
modeset = modeflag
includeonlyiorelated = includeonlyiorelatedFlag
planets = load('de421.bsp')
earthPlanet = planets['earth']
inidt = datetime.strptime(startdate, '%Y%m%d')
ts = load.timescale()
initDateUTC = ts.utc(inidt.year, inidt.month, inidt.day, 0.0, 0.0, 0.0 ).utc_datetime()
#print("initDateUTC: ", initDateUTC, type(initDateUTC))
ephemObsPos = ephem.Observer()
if radioConfig.stationLat[-1:] == "S":
lonSign = "-"
else:
lonSign = ""
ephemObsPos.lat = lonSign + radioConfig.stationLat[0:-2]
ephemObsPos.lon = radioConfig.stationLon[0:-2]
ephemObsPos.elev = radioConfig.stationElev
#To get U.S. Naval Astronomical Almanac values, use these settings
ephemObsPos.pressure= 0
# set the horizon that you want to use to one that is exactly 34 arcminutes lower
# than the normal horizon, to match the value by which the Navy reckons that
# an object at the horizon is refracted:
ephemObsPos.horizon = '-0:34'
myposition = earthPlanet + Topos(radioConfig.stationLat, radioConfig.stationLon)
print("pyephem observer position: ", ephemObsPos)
print("myposition: ", myposition)
# 1) the central meridian longitude of Jupiter that faces us
# 2) the position of the inner-most moon Io in its orbit around Jupiter
L3 = 0
U1 = 0
th = 0.0
predList = []
iterDateUTC = initDateUTC
finalDateUTC = initDateUTC + timedelta(days=(predictdays-1))
#external loop on requested days:
while iterDateUTC < finalDateUTC:
ephemObsPos.date = (iterDateUTC + + timedelta(hours=12) ).strftime('%Y-%m-%d %H:%M:%S')
JupiterRise = ephem2datetime(str(ephemObsPos.previous_rising(ephem.Jupiter())))
JupiterSet = ephem2datetime(str(ephemObsPos.next_setting (ephem.Jupiter())))
JupiterNextRise = ephem2datetime(str(ephemObsPos.next_rising(ephem.Jupiter())))
SunRise = ephem2datetime(str(ephemObsPos.next_rising(ephem.Sun())))
SunSet = ephem2datetime(str(ephemObsPos.next_setting(ephem.Sun())))
#internal loop within a single day
iterDateUTCtime = iterDateUTC
endOfDayUTCtime = iterDateUTC + timedelta(days=1)
while iterDateUTCtime < endOfDayUTCtime:
#this way i will do the other calcs only when Jupiter is above the local horizon and the Sun is not visible:
if ((iterDateUTCtime > JupiterRise and iterDateUTCtime < JupiterSet) or iterDateUTCtime > JupiterNextRise ) and (iterDateUTCtime < SunRise or iterDateUTCtime > SunSet):
calcforjd()
#calculate again every N minutes:
iterDateUTCtime = iterDateUTCtime + timedelta(minutes=calcinterval)
# since we have covered this day, let's go on with the next one:
iterDateUTC = iterDateUTC + timedelta(days=1)
return predList
#!/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 ts():
yield load.timescale()
# this source is part of my Hackster.io project: https://www.hackster.io/mariocannistra/radio-astronomy-with-rtl-sdr-raspberrypi-and-amazon-aws-iot-45b617
# this program will output the Jupiter-IO radio storm predictions in text format.
# It's a port to python of an older QBasic program whose original source can be found
# at http://www.spaceacademy.net.au/spacelab/projects/jovrad/jovrad.htm together with
# good explanations about the theory and instructions to build a folded dipole antenna.
import raforpi
from skyfield.api import load
import sys
from datetime import datetime, timedelta
from pytz import timezone
import radioConfig
from dateutil.relativedelta import relativedelta
# the section below needs deeper check on the involved formulas:
print('\nJovicentric Declination of Earth: (to be checked)')
eph = load('jup310.bsp')
jupiter = eph['jupiter']
earth = eph['earth']
deyear = 2000
while deyear < 2020:
initDateUTC = load.timescale().utc(deyear, 1, 1, 0.0, 0.0, 0.0 )
geometry = jupiter.at( initDateUTC ).observe(earth)
jcera, jcedec, jcedist = geometry.radec()
jcinfo = 'year {}\tjcedec {}'.format( initDateUTC.utc_datetime().strftime('%Y%m%d'), jcedec )
print(jcinfo)
deyear = deyear + 1
