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- #!/usr/bin/env python3
-
- from datetime import date as date_type
-
- from skyfield.errors import EphemerisRangeError
- from skyfield.timelib import Time
- from skyfield.searchlib import find_discrete, find_maxima, find_minima
- from numpy import pi
-
- from .data import Event, Star, Planet, ASTERS
- from .dateutil import translate_to_timezone
- from .enum import EventType
- from .exceptions import OutOfRangeDateError
- from .core import get_timescale, get_skf_objects, flatten_list
-
-
- def _search_conjunction(start_time: Time, end_time: Time, timezone: int) -> [Event]:
- earth = get_skf_objects()["earth"]
- aster1 = None
- aster2 = None
-
- def is_in_conjunction(time: Time):
- earth_pos = earth.at(time)
- _, aster1_lon, _ = (
- earth_pos.observe(aster1.get_skyfield_object()).apparent().ecliptic_latlon()
- )
- _, aster2_lon, _ = (
- earth_pos.observe(aster2.get_skyfield_object()).apparent().ecliptic_latlon()
- )
-
- return ((aster1_lon.radians - aster2_lon.radians) / pi % 2.0).astype(
- "int8"
- ) == 0
-
- is_in_conjunction.rough_period = 60.0
-
- computed = []
- conjunctions = []
-
- for aster1 in ASTERS:
- # Ignore the Sun
- if isinstance(aster1, Star):
- continue
-
- for aster2 in ASTERS:
- if isinstance(aster2, Star) or aster2 == aster1 or aster2 in computed:
- continue
-
- times, is_conjs = find_discrete(start_time, end_time, is_in_conjunction)
-
- for i, time in enumerate(times):
- if is_conjs[i]:
- aster1_pos = (aster1.get_skyfield_object() - earth).at(time)
- aster2_pos = (aster2.get_skyfield_object() - earth).at(time)
- distance = aster1_pos.separation_from(aster2_pos).degrees
-
- if distance - aster2.get_apparent_radius(
- time, earth
- ) < aster1.get_apparent_radius(time, earth):
- occulting_aster = (
- [aster1, aster2]
- if aster1_pos.distance().km < aster2_pos.distance().km
- else [aster2, aster1]
- )
-
- conjunctions.append(
- Event(
- EventType.OCCULTATION,
- occulting_aster,
- translate_to_timezone(time.utc_datetime(), timezone),
- )
- )
- else:
- conjunctions.append(
- Event(
- EventType.CONJUNCTION,
- [aster1, aster2],
- translate_to_timezone(time.utc_datetime(), timezone),
- )
- )
-
- computed.append(aster1)
-
- return conjunctions
-
-
- def _search_oppositions(start_time: Time, end_time: Time, timezone: int) -> [Event]:
- earth = get_skf_objects()["earth"]
- sun = get_skf_objects()["sun"]
- aster = None
-
- def is_oppositing(time: Time) -> [bool]:
- earth_pos = earth.at(time)
- sun_pos = earth_pos.observe(
- sun
- ).apparent() # Never do this without eyes protection!
- aster_pos = earth_pos.observe(get_skf_objects()[aster.skyfield_name]).apparent()
- _, lon1, _ = sun_pos.ecliptic_latlon()
- _, lon2, _ = aster_pos.ecliptic_latlon()
- return (lon1.degrees - lon2.degrees) > 180
-
- is_oppositing.rough_period = 1.0
- events = []
-
- for aster in ASTERS:
- if not isinstance(aster, Planet) or aster.skyfield_name in ["MERCURY", "VENUS"]:
- continue
-
- times, _ = find_discrete(start_time, end_time, is_oppositing)
- for time in times:
- events.append(
- Event(
- EventType.OPPOSITION,
- [aster],
- translate_to_timezone(time.utc_datetime(), timezone),
- )
- )
-
- return events
-
-
- def _search_maximal_elongations(
- start_time: Time, end_time: Time, timezone: int
- ) -> [Event]:
- earth = get_skf_objects()["earth"]
- sun = get_skf_objects()["sun"]
- aster = None
-
- def get_elongation(time: Time):
- sun_pos = (sun - earth).at(time)
- aster_pos = (aster.get_skyfield_object() - earth).at(time)
- separation = sun_pos.separation_from(aster_pos)
- return separation.degrees
-
- get_elongation.rough_period = 1.0
-
- events = []
-
- for aster in ASTERS:
- if aster.skyfield_name not in ["MERCURY", "VENUS"]:
- continue
-
- times, elongations = find_maxima(
- start_time, end_time, f=get_elongation, epsilon=1.0 / 24 / 3600, num=12
- )
-
- for i, time in enumerate(times):
- elongation = elongations[i]
- events.append(
- Event(
- EventType.MAXIMAL_ELONGATION,
- [aster],
- translate_to_timezone(time.utc_datetime(), timezone),
- details="{:.3n}°".format(elongation),
- )
- )
-
- return events
-
-
- def _get_moon_distance():
- earth = get_skf_objects()["earth"]
- moon = get_skf_objects()["moon"]
-
- def get_distance(time: Time):
- earth_pos = earth.at(time)
- moon_pos = earth_pos.observe(moon).apparent()
-
- return moon_pos.distance().au
-
- get_distance.rough_period = 1.0
-
- return get_distance
-
-
- def _search_moon_apogee(start_time: Time, end_time: Time, timezone: int) -> [Event]:
- moon = ASTERS[1]
- events = []
-
- times, _ = find_maxima(
- start_time, end_time, f=_get_moon_distance(), epsilon=1.0 / 24 / 60
- )
-
- for time in times:
- events.append(
- Event(
- EventType.MOON_APOGEE,
- [moon],
- translate_to_timezone(time.utc_datetime(), timezone),
- )
- )
-
- return events
-
-
- def _search_moon_perigee(start_time: Time, end_time: Time, timezone: int) -> [Event]:
- moon = ASTERS[1]
- events = []
-
- times, _ = find_minima(
- start_time, end_time, f=_get_moon_distance(), epsilon=1.0 / 24 / 60
- )
-
- for time in times:
- events.append(
- Event(
- EventType.MOON_PERIGEE,
- [moon],
- translate_to_timezone(time.utc_datetime(), timezone),
- )
- )
-
- return events
-
-
- def get_events(date: date_type = date_type.today(), timezone: int = 0) -> [Event]:
- """Calculate and return a list of events for the given date, adjusted to the given timezone if any.
-
- Find events that happen on April 4th, 2020 (show hours in UTC):
-
- >>> get_events(date_type(2020, 4, 4))
- [<Event type=CONJUNCTION objects=[<Object type=PLANET name=MERCURY />, <Object type=PLANET name=NEPTUNE />] start=2020-04-04 01:14:39.063308+00:00 end=None details=None />]
-
- Find events that happen on April 4th, 2020 (show timezones in UTC+2):
-
- >>> get_events(date_type(2020, 4, 4), 2)
- [<Event type=CONJUNCTION objects=[<Object type=PLANET name=MERCURY />, <Object type=PLANET name=NEPTUNE />] start=2020-04-04 03:14:39.063267+02:00 end=None details=None />]
-
- Find events that happen on April 3rd, 2020 (show timezones in UTC-2):
-
- >>> get_events(date_type(2020, 4, 3), -2)
- [<Event type=CONJUNCTION objects=[<Object type=PLANET name=MERCURY />, <Object type=PLANET name=NEPTUNE />] start=2020-04-03 23:14:39.063388-02:00 end=None details=None />]
-
- :param date: the date for which the events must be calculated
- :param timezone: the timezone to adapt the results to. If not given, defaults to 0.
- :return: a list of events found for the given date.
- """
-
- start_time = get_timescale().utc(date.year, date.month, date.day, -timezone)
- end_time = get_timescale().utc(date.year, date.month, date.day + 1, -timezone)
-
- try:
- found_events = []
-
- for fun in [
- _search_oppositions,
- _search_conjunction,
- _search_maximal_elongations,
- _search_moon_apogee,
- _search_moon_perigee,
- ]:
- found_events.append(fun(start_time, end_time, timezone))
-
- return sorted(flatten_list(found_events), key=lambda event: event.start_time)
- except EphemerisRangeError as error:
- start_date = translate_to_timezone(error.start_time.utc_datetime(), timezone)
- end_date = translate_to_timezone(error.end_time.utc_datetime(), timezone)
-
- start_date = date_type(start_date.year, start_date.month, start_date.day)
- end_date = date_type(end_date.year, end_date.month, end_date.day)
-
- raise OutOfRangeDateError(start_date, end_date) from error
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