A library that computes the ephemerides.
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ephemerides.py 6.9 KiB

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  1. #!/usr/bin/env python3
  2. import datetime
  3. from typing import Union
  4. from skyfield.searchlib import find_discrete, find_maxima
  5. from skyfield.timelib import Time
  6. from skyfield.constants import tau
  7. from skyfield.errors import EphemerisRangeError
  8. from .data import Position, AsterEphemerides, MoonPhase, Object, ASTERS
  9. from .dateutil import translate_to_timezone
  10. from .core import get_skf_objects, get_timescale, get_iau2000b
  11. from .enum import MoonPhaseType
  12. from .exceptions import OutOfRangeDateError
  13. RISEN_ANGLE = -0.8333
  14. def _get_skyfield_to_moon_phase(
  15. times: [Time], vals: [int], now: Time, timezone: int
  16. ) -> Union[MoonPhase, None]:
  17. tomorrow = get_timescale().utc(
  18. now.utc_datetime().year, now.utc_datetime().month, now.utc_datetime().day + 1
  19. )
  20. phases = list(MoonPhaseType)
  21. current_phase = None
  22. current_phase_time = None
  23. next_phase_time = None
  24. i = 0
  25. if len(times) == 0:
  26. return None
  27. for i, time in enumerate(times):
  28. if now.utc_iso() <= time.utc_iso():
  29. if vals[i] in [0, 2, 4, 6]:
  30. if time.utc_datetime() < tomorrow.utc_datetime():
  31. current_phase_time = time
  32. current_phase = phases[vals[i]]
  33. else:
  34. i -= 1
  35. current_phase_time = None
  36. current_phase = phases[vals[i]]
  37. else:
  38. current_phase = phases[vals[i]]
  39. break
  40. for j in range(i + 1, len(times)):
  41. if vals[j] in [0, 2, 4, 6]:
  42. next_phase_time = times[j]
  43. break
  44. return MoonPhase(
  45. current_phase,
  46. translate_to_timezone(current_phase_time.utc_datetime(), timezone) if current_phase_time is not None else None,
  47. translate_to_timezone(next_phase_time.utc_datetime(), timezone) if next_phase_time is not None else None,
  48. )
  49. def get_moon_phase(
  50. for_date: datetime.date = datetime.date.today(), timezone: int = 0
  51. ) -> MoonPhase:
  52. """Calculate and return the moon phase for the given date, adjusted to the given timezone if any.
  53. Get the moon phase for the 27 March, 2021:
  54. >>> get_moon_phase(datetime.date.fromisoformat("2021-03-27"))
  55. <MoonPhase phase_type=MoonPhaseType.WAXING_GIBBOUS time=None next_phase_date=2021-03-28 18:48:10.902298+00:00>
  56. Get the moon phase for the 27 March, 2021, in the UTC+2 timezone:
  57. >>> get_moon_phase(datetime.date.fromisoformat("2021-03-27"), timezone=2)
  58. <MoonPhase phase_type=MoonPhaseType.WAXING_GIBBOUS time=None next_phase_date=2021-03-28 20:48:10.902298+02:00>
  59. """
  60. earth = get_skf_objects()["earth"]
  61. moon = get_skf_objects()["moon"]
  62. sun = get_skf_objects()["sun"]
  63. def moon_phase_at(time: Time):
  64. time._nutation_angles = get_iau2000b(time)
  65. current_earth = earth.at(time)
  66. _, mlon, _ = current_earth.observe(moon).apparent().ecliptic_latlon("date")
  67. _, slon, _ = current_earth.observe(sun).apparent().ecliptic_latlon("date")
  68. return (((mlon.radians - slon.radians) // (tau / 8)) % 8).astype(int)
  69. moon_phase_at.rough_period = 7.0 # one lunar phase per week
  70. today = get_timescale().utc(for_date.year, for_date.month, for_date.day)
  71. time1 = get_timescale().utc(
  72. for_date.year, for_date.month, for_date.day - 10
  73. )
  74. time2 = get_timescale().utc(
  75. for_date.year, for_date.month, for_date.day + 10
  76. )
  77. try:
  78. times, phase = find_discrete(time1, time2, moon_phase_at)
  79. except EphemerisRangeError as error:
  80. start = translate_to_timezone(error.start_time.utc_datetime(), timezone)
  81. end = translate_to_timezone(error.end_time.utc_datetime(), timezone)
  82. start = datetime.date(start.year, start.month, start.day) + datetime.timedelta(
  83. days=12
  84. )
  85. end = datetime.date(end.year, end.month, end.day) - datetime.timedelta(days=12)
  86. raise OutOfRangeDateError(start, end) from error
  87. return _get_skyfield_to_moon_phase(times, phase, today, timezone)
  88. def get_ephemerides(
  89. position: Position, date: datetime.date = datetime.date.today(), timezone: int = 0
  90. ) -> [AsterEphemerides]:
  91. ephemerides = []
  92. def get_angle(for_aster: Object):
  93. def fun(time: Time) -> float:
  94. return (
  95. position.get_planet_topos()
  96. .at(time)
  97. .observe(for_aster.get_skyfield_object())
  98. .apparent()
  99. .altaz()[0]
  100. .degrees
  101. )
  102. fun.rough_period = 1.0
  103. return fun
  104. def is_risen(for_aster: Object):
  105. def fun(time: Time) -> bool:
  106. return get_angle(for_aster)(time) > RISEN_ANGLE
  107. fun.rough_period = 0.5
  108. return fun
  109. start_time = get_timescale().utc(date.year, date.month, date.day, -timezone)
  110. end_time = get_timescale().utc(
  111. date.year, date.month, date.day, 23 - timezone, 59, 59
  112. )
  113. try:
  114. for aster in ASTERS:
  115. rise_times, arr = find_discrete(start_time, end_time, is_risen(aster))
  116. try:
  117. culmination_time, _ = find_maxima(
  118. start_time,
  119. end_time,
  120. f=get_angle(aster),
  121. epsilon=1.0 / 3600 / 24,
  122. num=12,
  123. )
  124. culmination_time = (
  125. culmination_time[0] if len(culmination_time) > 0 else None
  126. )
  127. except ValueError:
  128. culmination_time = None
  129. if len(rise_times) == 2:
  130. rise_time = rise_times[0 if arr[0] else 1]
  131. set_time = rise_times[1 if not arr[1] else 0]
  132. else:
  133. rise_time = rise_times[0] if arr[0] else None
  134. set_time = rise_times[0] if not arr[0] else None
  135. # Convert the Time instances to Python datetime objects
  136. if rise_time is not None:
  137. rise_time = translate_to_timezone(
  138. rise_time.utc_datetime().replace(microsecond=0), to_tz=timezone
  139. )
  140. if culmination_time is not None:
  141. culmination_time = translate_to_timezone(
  142. culmination_time.utc_datetime().replace(microsecond=0),
  143. to_tz=timezone,
  144. )
  145. if set_time is not None:
  146. set_time = translate_to_timezone(
  147. set_time.utc_datetime().replace(microsecond=0), to_tz=timezone
  148. )
  149. ephemerides.append(
  150. AsterEphemerides(rise_time, culmination_time, set_time, aster=aster)
  151. )
  152. except EphemerisRangeError as error:
  153. start = translate_to_timezone(error.start_time.utc_datetime(), timezone)
  154. end = translate_to_timezone(error.end_time.utc_datetime(), timezone)
  155. start = datetime.date(start.year, start.month, start.day + 1)
  156. end = datetime.date(end.year, end.month, end.day - 1)
  157. raise OutOfRangeDateError(start, end) from error
  158. return ephemerides