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feat(events): add support for lunar eclipses (#28)

tags/v1.0.0
Jérôme Deuchnord 3 years ago
committed by Jérôme Deuchnord
parent
commit
f43d6043b0
No known key found for this signature in database GPG Key ID: 9F72B1EF93EDE1D4
2 changed files with 91 additions and 4 deletions
  1. +9
    -0
      kosmorrolib/enum.py
  2. +82
    -4
      kosmorrolib/events.py

+ 9
- 0
kosmorrolib/enum.py View File

@@ -49,6 +49,15 @@ class EventType(Enum):
MOON_PERIGEE = 5
MOON_APOGEE = 6
SEASON_CHANGE = 7
LUNAR_ECLIPSE = 8


class LunarEclipseType(Enum):
"""An enumeration of lunar eclipse types"""

PENUMBRAL = 0
PARTIAL = 1
TOTAL = 2


class ObjectType(Enum):


+ 82
- 4
kosmorrolib/events.py View File

@@ -16,17 +16,18 @@
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.

from datetime import date
from datetime import date, timedelta

from skyfield.errors import EphemerisRangeError
from skyfield.timelib import Time
from skyfield.searchlib import find_discrete, find_maxima, find_minima
from skyfield import almanac
from skyfield.units import Angle
from skyfield import almanac, eclipselib
from numpy import pi

from kosmorrolib.model import Event, Star, Planet, ASTERS
from kosmorrolib.model import Event, Star, Planet, ASTERS, EARTH
from kosmorrolib.dateutil import translate_to_timezone
from kosmorrolib.enum import EventType, ObjectIdentifier, SeasonType
from kosmorrolib.enum import EventType, ObjectIdentifier, SeasonType, LunarEclipseType
from kosmorrolib.exceptions import OutOfRangeDateError
from kosmorrolib.core import get_timescale, get_skf_objects, flatten_list

@@ -318,6 +319,82 @@ def _search_earth_season_change(
return events


def _search_lunar_eclipse(start_time: Time, end_time: Time, timezone: int) -> [Event]:
"""Function to detect lunar eclipses.

**Warning:** this is an internal function, not intended for use by end-developers.

Will return a total lunar eclipse for 2021-05-26:

>>> _search_lunar_eclipse(get_timescale().utc(2021, 5, 26), get_timescale().utc(2021, 5, 27), 0)
[<Event type=LUNAR_ECLIPSE objects=[<Object type=SATELLITE name=MOON />] start=2021-05-26 08:47:54.795821+00:00 end=2021-05-26 13:49:34.353411+00:00 details={'type': <LunarEclipseType.TOTAL: 2>, 'maximum': datetime.datetime(2021, 5, 26, 11, 18, 42, 328842, tzinfo=datetime.timezone.utc)} />]

>>> _search_lunar_eclipse(get_timescale().utc(2019, 7, 16), get_timescale().utc(2019, 7, 17), 0)
[<Event type=LUNAR_ECLIPSE objects=[<Object type=SATELLITE name=MOON />] start=2019-07-16 18:39:53.391337+00:00 end=2019-07-17 00:21:51.378940+00:00 details={'type': <LunarEclipseType.PARTIAL: 1>, 'maximum': datetime.datetime(2019, 7, 16, 21, 30, 44, 170096, tzinfo=datetime.timezone.utc)} />]

>>> _search_lunar_eclipse(get_timescale().utc(2017, 2, 11), get_timescale().utc(2017, 2, 12), 0)
[<Event type=LUNAR_ECLIPSE objects=[<Object type=SATELLITE name=MOON />] start=2017-02-10 22:02:59.016572+00:00 end=2017-02-11 03:25:07.627886+00:00 details={'type': <LunarEclipseType.PENUMBRAL: 0>, 'maximum': datetime.datetime(2017, 2, 11, 0, 43, 51, 793786, tzinfo=datetime.timezone.utc)} />]
"""
moon = ASTERS[1]
events = []
t, y, details = eclipselib.lunar_eclipses(start_time, end_time, get_skf_objects())

for ti, yi in zip(t, y):
penumbra_radius = Angle(radians=details["penumbra_radius_radians"][0])
_, max_lon, _ = (
EARTH.get_skyfield_object()
.at(ti)
.observe(moon.get_skyfield_object())
.apparent()
.ecliptic_latlon()
)

def is_in_penumbra(time: Time):
_, lon, _ = (
EARTH.get_skyfield_object()
.at(time)
.observe(moon.get_skyfield_object())
.apparent()
.ecliptic_latlon()
)

moon_radius = details["moon_radius_radians"]

return (
abs(max_lon.radians - lon.radians)
< penumbra_radius.radians + moon_radius
)

is_in_penumbra.rough_period = 60.0

search_start_time = get_timescale().from_datetime(
start_time.utc_datetime() - timedelta(days=1)
)
search_end_time = get_timescale().from_datetime(
end_time.utc_datetime() + timedelta(days=1)
)

eclipse_start, _ = find_discrete(search_start_time, ti, is_in_penumbra)
eclipse_end, _ = find_discrete(ti, search_end_time, is_in_penumbra)

events.append(
Event(
EventType.LUNAR_ECLIPSE,
[moon],
start_time=translate_to_timezone(
eclipse_start[0].utc_datetime(), timezone
),
end_time=translate_to_timezone(eclipse_end[0].utc_datetime(), timezone),
details={
"type": LunarEclipseType(yi),
"maximum": translate_to_timezone(ti.utc_datetime(), timezone),
},
)
)

return events


def get_events(for_date: date = date.today(), timezone: int = 0) -> [Event]:
"""Calculate and return a list of events for the given date, adjusted to the given timezone if any.

@@ -363,6 +440,7 @@ def get_events(for_date: date = date.today(), timezone: int = 0) -> [Event]:
_search_moon_apogee,
_search_moon_perigee,
_search_earth_season_change,
_search_lunar_eclipse,
]:
found_events.append(fun(start_time, end_time, timezone))



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