How to use the skyfield.api function in skyfield

from sqlalchemy import func
from model import *
from server import app

from datetime import datetime
from skyfield import api, almanac
import itertools

TS = api.load.timescale(builtin=True)
E = api.load('seed_data/de421.bsp')


def test_data():
    test_moon_phase_type()
    test_full_moon_nickname()
    test_solstices()
    test_moon_phase_occurences()
    test_user()


##################################
### TEST DATA HELPER FUNCTIONS ###
##################################


def test_moon_phase_type():

from sqlalchemy import func
from model import *
from server import app

from datetime import datetime
from skyfield import api, almanac
import itertools

TS = api.load.timescale(builtin=True)
E = api.load('seed_data/de421.bsp')


def test_data():
    test_moon_phase_type()
    test_full_moon_nickname()
    test_solstices()
    test_moon_phase_occurences()
    test_user()


##################################
### TEST DATA HELPER FUNCTIONS ###
##################################

"""
On my laptop, this script shows that simply computing the positions and
the sunlit-ness of the ISS for each of the 381 seconds of this pass
takes roughly the same amount of time as mounting a full search for the
moment it passes into shadow.  But the benefit is far greater, because
with almost no additional expense all altitudes and azimuths can also
be computed.

"""
import numpy as np
from skyfield import almanac, api
from skyfield.nutationlib import iau2000b

ts = api.load.timescale(builtin=True)
eph = api.load('de421.bsp')
sat = api.EarthSatellite(
    '1 25544U 98067A   20150.54009403  .00000886  00000-0  23936-4 0  9992',
    '2 25544  51.6447  80.7632 0002782   3.7438 167.9307 15.49399736229124',
)

topos = api.Topos('18.3368 N', '64.7281 W')
t0 = ts.utc(2020, 6, 5)
t1 = ts.utc(2020, 6, 6)

half_second = 0.5 / 24.0 / 3600.0

from time import time

T0 = time()
t, y = sat.find_events(topos, t0, t1, altitude_degrees=10.0)

from sqlalchemy import func
from model import User, MoonPhaseType, MoonPhaseOccurence, Solstice, FullMoonNickname, Alert, connect_to_db, db
from server import app

from datetime import datetime
from skyfield import api, almanac
import itertools
from seed_data.moon_phase_descriptions import moon_phases_dict

MOON_PHASE_TYPES = ['New Moon', 'First Quarter', 'Full Moon', 'Last Quarter']
FULL_MOON_NICKNAMES = ['Wolf Moon', 'Snow Moon', 'Worm Moon', 'Pink Moon', 'Flower Moon', 'Strawberry Moon', 'Buck Moon', 'Sturgeon Moon', 'Corn Moon', "Hunter's Moon", 'Beaver Moon', 'Cold Moon']
MOON_EMOJIS = ['🌚','🌛', '🌝','🌜']
TS = api.load.timescale(builtin=True)
E = api.load('seed_data/de421.bsp')


def load_moon_phase_types():
    """Adds moon phase types to moon phase types table"""

    for moon_phase, moon_emoji in zip(MOON_PHASE_TYPES, MOON_EMOJIS):
        moon_phase_type = MoonPhaseType(title=moon_phase, description=moon_phases_dict[moon_phase], emoji=moon_emoji)
        db.session.add(moon_phase_type)

    db.session.commit

def load_full_moon_nicknames():
    """Adds full moon nicknames to moon phase nicknames table"""

    for (nickname, month) in zip(FULL_MOON_NICKNAMES, range(1, 13)):

def compute(target, kernel=de421, name=None, topo=None, t=None, planet=0,
            precision_radec=15, precision_azalt=120, klass=None, json=None):
    ts = sf.load.timescale()
    if isinstance(target, str):
        name = target
        target = kernel[target]

    if topo is None:
        topo = ['33.7490 N', '84.3880 W'] # Atlanta.
    topo = sf.Topos(*topo)

    if t is None:
        t = [2019, 9, 6, 17, 0, 0]
    t = ts.utc(*t)
    if name is None:
        name = target.target_name
    if not planet and isinstance(target.target, int):
        planet = target.target

    earth = de421['earth']
    obs = (earth + topo).at(t)
    pos = obs.observe(target)
    geo = earth.at(t).observe(target)
    radec = pos.radec(t)
    altaz = pos.apparent().altaz()
    # skyfield use JD, ephemeride uses Modified JD.

with almost no additional expense all altitudes and azimuths can also
be computed.

"""
import numpy as np
from skyfield import almanac, api
from skyfield.nutationlib import iau2000b

ts = api.load.timescale(builtin=True)
eph = api.load('de421.bsp')
sat = api.EarthSatellite(
    '1 25544U 98067A   20150.54009403  .00000886  00000-0  23936-4 0  9992',
    '2 25544  51.6447  80.7632 0002782   3.7438 167.9307 15.49399736229124',
)

topos = api.Topos('18.3368 N', '64.7281 W')
t0 = ts.utc(2020, 6, 5)
t1 = ts.utc(2020, 6, 6)

half_second = 0.5 / 24.0 / 3600.0

from time import time

T0 = time()
t, y = sat.find_events(topos, t0, t1, altitude_degrees=10.0)
print(time() - T0, 'seconds to find events:')

for ti, yi in zip(t, y):
    print(' ', ti.utc_jpl(), yi)

offset = 0
assert list(y[offset:offset+3]) == [0, 1, 2]

df['mean_anomaly_degrees'] = (
    sqrt(mu_au3_d2 / (row.semimajor_axis_au ** 3.0))
    *
    (ts.J2000.tt - t_perihelion.tt)
    * 360.0 / tau
)

comet = df.iloc[0:1]

k = KeplerOrbit.from_comet_dataframe(ts, comet.ix[0])

from skyfield.data.spice import inertial_frames

from math import sqrt

eph = api.load('de421.bsp')
t = ts.utc(2020, 5, 31)

k._rotation = inertial_frames['ECLIPJ2000'].T

p = eph['earth'].at(t).observe(eph['sun'] + k)
ra, dec, distance = p.radec()

print(t.utc_iso(' '))
print(ra, '   ("23 59 16.6")')
print(dec, '  ("-84 46 58")')
print(distance)

"""
Below are the results of your request from the Minor Planet Center's Minor Planet Ephemeris Service. Ephemerides are for the geocenter.

import sys
from numpy import array, mean, std, zeros
from skyfield import earthlib, nutationlib, api, starlib

from skyfield.constants import T0
from skyfield.timelib import julian_date, Time
from timeit import default_timer

TA = julian_date(1969, 7, 20, 20., 18.)
TB = julian_date(2012, 12, 21)

D0 = 63.8285
DA = 39.707
DB = 66.8779

earth = api.earth
jupiter = api.jupiter
star = starlib.Star(
    ra_hours=1.59132070233, dec_degrees=8.5958876464,
    ra_mas_per_year=0.0, dec_mas_per_year=0.0,
    parallax_mas=0.0, radial_km_per_s=0.0,
    )


class BM(object):
    def __init__(self, times, bm_fn, t):
        self.name = bm_fn.__name__
        self.times = times
        self.bm_fn = bm_fn
        self.t = t

    def __call__(self):

from numpy import array, mean, std, zeros
from skyfield import earthlib, nutationlib, api, starlib

from skyfield.constants import T0
from skyfield.timelib import julian_date, Time
from timeit import default_timer

TA = julian_date(1969, 7, 20, 20., 18.)
TB = julian_date(2012, 12, 21)

D0 = 63.8285
DA = 39.707
DB = 66.8779

earth = api.earth
jupiter = api.jupiter
star = starlib.Star(
    ra_hours=1.59132070233, dec_degrees=8.5958876464,
    ra_mas_per_year=0.0, dec_mas_per_year=0.0,
    parallax_mas=0.0, radial_km_per_s=0.0,
    )


class BM(object):
    def __init__(self, times, bm_fn, t):
        self.name = bm_fn.__name__
        self.times = times
        self.bm_fn = bm_fn
        self.t = t

    def __call__(self):
        self.bm_fn(self.times, self.t)

def __init__(self):
        """Create Alignment instance. See class documentation."""
        self._target = None
        self._rise_time = None
        self._set_time = None

        self._tle_line1 = None
        self._tle_line2 = None
        self._skyfield_ts = sf_api.Loader(_system_data_dir, expire=False).timescale()