Merge pull request #59 from Deuchnord/fix-conjunctions

Prevent false detection of conjunctions

kosmorrolib/events.py

@@ -20,6 +20,7 @@ from datetime import date as date_type
 
 from skyfield.timelib import Time
 from skyfield.searchlib import find_discrete, find_maxima
+from numpy import pi
 
 from .data import Event, Planet, ASTERS
 from .core import get_timescale, get_skf_objects, flatten_list
@@ -32,15 +33,12 @@ def _search_conjunction(start_time: Time, end_time: Time) -> [Event]:
 
     def is_in_conjunction(time: Time):
         earth_pos = earth.at(time)
-        aster1_pos = earth_pos.observe(get_skf_objects()[aster1.skyfield_name]).apparent()
-        aster2_pos = earth_pos.observe(get_skf_objects()[aster2.skyfield_name]).apparent()
+        _, aster1_lon, _ = earth_pos.observe(aster1.get_skyfield_object()).apparent().ecliptic_latlon()
+        _, aster2_lon, _ = earth_pos.observe(aster2.get_skyfield_object()).apparent().ecliptic_latlon()
 
-        aster_1_right_ascension, _, _ = aster1_pos.radec()
-        aster_2_right_ascension, _, _ = aster2_pos.radec()
+        return ((aster1_lon.radians - aster2_lon.radians) / pi % 2.0).astype('int8') == 0
 
-        return aster_1_right_ascension.hours - aster_2_right_ascension.hours < 0
-
-    is_in_conjunction.rough_period = 1.0
+    is_in_conjunction.rough_period = 60.0
 
     computed = []
     conjunctions = []
@@ -54,10 +52,11 @@ def _search_conjunction(start_time: Time, end_time: Time) -> [Event]:
             if not isinstance(aster2, Planet) or aster2 == aster1 or aster2 in computed:
                 continue
 
-            times, _ = find_discrete(start_time, end_time, is_in_conjunction)
+            times, is_conjs = find_discrete(start_time, end_time, is_in_conjunction)
 
-            for time in times:
-                conjunctions.append(Event('CONJUNCTION', [aster1, aster2], time.utc_datetime()))
+            for i, time in enumerate(times):
+                if is_conjs[i]:
+                    conjunctions.append(Event('CONJUNCTION', [aster1, aster2], time.utc_datetime()))
 
         computed.append(aster1)
 

test/events.py

@@ -29,11 +29,16 @@ class MyTestCase(unittest.TestCase):
             self.assertEqual('Mars is in opposition', o[0].get_description())
 
     def test_find_conjunctions(self):
-        # Test case: Mars opposition
-        # Source of the information: https://promenade.imcce.fr/en/pages6/887.html#mar
-        c1 = (events.search_events(date(2020, 1, 2)), [(['MERCURY', 'JUPITER BARYCENTER'], '^2020-01-02T15:20')])
-        c2 = (events.search_events(date(2020, 1, 12)), [(['MERCURY', 'SATURN BARYCENTER'], '^2020-01-12T04:34'),
-                                                        (['MERCURY', 'PLUTO BARYCENTER'], '^2020-01-12T06:56')])
+        MERCURY = 'MERCURY'
+        JUPITER = 'JUPITER BARYCENTER'
+        SATURN = 'SATURN BARYCENTER'
+        PLUTO = 'PLUTO BARYCENTER'
+
+        c1 = (events.search_events(date(2020, 1, 2)), [([MERCURY, JUPITER], '^2020-01-02T16:41')])
+        c2 = (events.search_events(date(2020, 1, 12)), [([MERCURY, SATURN], '^2020-01-12T09:51'),
+                                                        ([MERCURY, PLUTO], '^2020-01-12T10:13'),
+                                                        ([SATURN, PLUTO], '^2020-01-12T16:57')])
+        c3 = (events.search_events(date(2020, 2, 7)), [])
 
         for (c, expected_dates) in [c1, c2]:
             self.assertEqual(len(expected_dates), len(c),