Nutze Skyfield fuer praezisere Daemmerungsberechnung

public/py/astronomical_conversions.py

@@ -1,10 +1,20 @@
 #!/usr/bin/env python3
 import math
+import os
+import sys
 from datetime import datetime, timedelta, timezone
 from decimal import Decimal, InvalidOperation, ROUND_HALF_UP, localcontext
 from zoneinfo import ZoneInfo
 
 import astronomy
+SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
+VENDOR_DIR = os.path.join(SCRIPT_DIR, "vendor")
+VENDOR_DATA_DIR = os.path.join(SCRIPT_DIR, "vendor_data")
+SKYFIELD_EPHEMERIS_PATH = os.path.join(VENDOR_DATA_DIR, "de421.bsp")
+
+if VENDOR_DIR not in sys.path:
+    sys.path.insert(0, VENDOR_DIR)
+
 try:
     from astropy.time import Time as AstropyTime
     ASTROPY_AVAILABLE = True
@@ -12,6 +22,15 @@ except ImportError:
     AstropyTime = None
     ASTROPY_AVAILABLE = False
 
+try:
+    from skyfield.api import load as skyfield_load
+    from skyfield.api import wgs84 as skyfield_wgs84
+    SKYFIELD_AVAILABLE = True
+except ImportError:
+    skyfield_load = None
+    skyfield_wgs84 = None
+    SKYFIELD_AVAILABLE = False
+
 SPEED_OF_LIGHT_KM_S = 299792.458
 H0 = 70.0
 OMEGA_M = 0.3
@@ -102,6 +121,9 @@ EQ_TO_GAL_MATRIX = (
     (-0.8676661490190047, -0.1980763734312015, 0.4559837761750669),
 )
 
+_SKYFIELD_TIMESCALE = None
+_SKYFIELD_PLANETS = None
+
 
 def parse_decimal_input(value: str) -> Decimal | None:
     text = str(value or "").strip()
@@ -177,6 +199,32 @@ def normalize_angle_degrees(value: float) -> float:
     return normalized
 
 
+def skyfield_context() -> tuple[object, object]:
+    global _SKYFIELD_TIMESCALE, _SKYFIELD_PLANETS
+
+    if not SKYFIELD_AVAILABLE:
+        raise RuntimeError("Skyfield ist lokal nicht verfuegbar.")
+
+    if not os.path.exists(SKYFIELD_EPHEMERIS_PATH):
+        raise RuntimeError("Die lokale Skyfield-Ephemeride de421.bsp fehlt.")
+
+    if _SKYFIELD_TIMESCALE is None:
+        _SKYFIELD_TIMESCALE = skyfield_load.timescale()
+
+    if _SKYFIELD_PLANETS is None:
+        _SKYFIELD_PLANETS = skyfield_load(SKYFIELD_EPHEMERIS_PATH)
+
+    return _SKYFIELD_TIMESCALE, _SKYFIELD_PLANETS
+
+
+def calculate_solar_altaz_skyfield(dt_utc: datetime, latitude: float, longitude: float) -> tuple[float, float]:
+    timescale, planets = skyfield_context()
+    time_value = timescale.from_datetime(dt_utc.astimezone(timezone.utc))
+    observer = planets["earth"] + skyfield_wgs84.latlon(latitude, longitude)
+    altitude, azimuth, _distance = observer.at(time_value).observe(planets["sun"]).apparent().altaz()
+    return float(altitude.degrees), float(azimuth.degrees)
+
+
 def transpose_matrix(matrix: tuple[tuple[float, float, float], ...]) -> tuple[tuple[float, float, float], ...]:
     return tuple(tuple(matrix[row][column] for row in range(3)) for column in range(3))
 
@@ -557,15 +605,21 @@ def convert_tools(payload: dict) -> dict:
         return {"valid": False, "fields": {key: "" for key in TOOLS_ORDER}}
 
     dt_utc = local_dt.astimezone(timezone.utc)
-    time_value = dt_to_time(dt_utc)
-    observer = astronomy.Observer(latitude, longitude, 0.0)
-    equator = astronomy.Equator(astronomy.Body.Sun, time_value, observer, True, True)
-    horizon = astronomy.Horizon(time_value, observer, equator.ra, equator.dec, astronomy.Refraction.Normal)
+
+    try:
+        altitude_deg, azimuth_deg = calculate_solar_altaz_skyfield(dt_utc, latitude, longitude)
+    except Exception:
+        time_value = dt_to_time(dt_utc)
+        observer = astronomy.Observer(latitude, longitude, 0.0)
+        equator = astronomy.Equator(astronomy.Body.Sun, time_value, observer, True, True)
+        horizon = astronomy.Horizon(time_value, observer, equator.ra, equator.dec, astronomy.Refraction.Normal)
+        altitude_deg = float(horizon.altitude)
+        azimuth_deg = float(horizon.azimuth)
 
     fields = {
         "utc": format_utc_datetime(dt_utc),
-        "altitude": format_decimal_german(horizon.altitude, max_fraction_digits=4),
-        "azimuth": format_decimal_german(normalize_angle_degrees(horizon.azimuth), max_fraction_digits=4),
+        "altitude": format_decimal_german(altitude_deg, max_fraction_digits=4),
+        "azimuth": format_decimal_german(normalize_angle_degrees(azimuth_deg), max_fraction_digits=4),
     }
     return {"valid": True, "fields": fields}