TMSS-459: Add new endpoint 'angular_separation_from_bodies' and backend logic...

TMSS-459: Add new endpoint 'angular_separation_from_bodies' and backend logic to calculate distance of a pointing from solar system bodies

SAS/TMSS/src/tmss/tmssapp/conversions.py

@@ -3,8 +3,9 @@ import astropy.units
 from lofar.lta.sip import station_coordinates
 from datetime import datetime
 from astropy.coordinates.earth import EarthLocation
-from astropy.coordinates import Angle
+from astropy.coordinates import Angle, get_body
 from astroplan.observer import Observer
+import astropy.time
 
 
 def create_astroplan_observer_for_station(station: str) -> Observer:
@@ -26,18 +27,18 @@ def timestamps_and_stations_to_sun_rise_and_set(timestamps: [datetime], stations
     """
     compute sunrise, sunset, day and night of the given stations at the given timestamps
     :param timestamps: list of datetimes, e.g. [datetime(2020, 1, 1), datetime(2020, 1, 2)]
-    :param stations: list of station names, e.g. ["CS001"]
+    :param stations: list of station names, e.g. ["CS002"]
     :return A dict that maps station names to a nested dict that contains lists of start and end times for sunrise, sunset, etc, on each requested date.
         E.g.
-        {"CS001":
-            {   "sunrise": [{"start": (2020, 1, 1, 6, 0, 0)), "end": (2020, 1, 1, 6, 30, 0)},
-                            {"start": (2020, 1, 2, 6, 0, 0)), "end": (2020, 1, 2, 6, 30, 0)}],
-                "sunset": [{"start": (2020, 1, 1, 18, 0, 0)), "end": (2020, 1, 1, 18, 30, 0)},
-                           {"start": (2020, 1, 2, 18, 0, 0)), "end": (2020, 1, 2, 18, 30, 0)}],
-                "day": [{"start": (2020, 1, 1, 6, 30, 0)), "end": (2020, 1, 1, 18, 00, 0)},
-                        {"start": (2020, 1, 2, 6, 30, 0)), "end": (2020, 1, 2, 18, 00, 0)}],
-                "night": [{"start": (2020, 1, 1, 18, 30, 0)), "end": (2020, 1, 2, 6, 0, 0)},
-                          {"start": (2020, 1, 2, 18,3 0, 0)), "end": (2020, 1, 3, 6, 0, 0)}],
+        {"CS002":
+            {   "sunrise": [{"start": datetime(2020, 1, 1, 6, 0, 0)), "end": datetime(2020, 1, 1, 6, 30, 0)},
+                            {"start": datetime(2020, 1, 2, 6, 0, 0)), "end": datetime(2020, 1, 2, 6, 30, 0)}],
+                "sunset": [{"start": datetime(2020, 1, 1, 18, 0, 0)), "end": datetime(2020, 1, 1, 18, 30, 0)},
+                           {"start": datetime(2020, 1, 2, 18, 0, 0)), "end": datetime(2020, 1, 2, 18, 30, 0)}],
+                "day": [{"start": datetime(2020, 1, 1, 6, 30, 0)), "end": datetime(2020, 1, 1, 18, 00, 0)},
+                        {"start": datetime(2020, 1, 2, 6, 30, 0)), "end": datetime(2020, 1, 2, 18, 00, 0)}],
+                "night": [{"start": datetime(2020, 1, 1, 18, 30, 0)), "end": datetime(2020, 1, 2, 6, 0, 0)},
+                          {"start": datetime(2020, 1, 2, 18,3 0, 0)), "end": datetime(2020, 1, 3, 6, 0, 0)}],
             }
         }
     """
@@ -59,6 +60,39 @@ def timestamps_and_stations_to_sun_rise_and_set(timestamps: [datetime], stations
     return return_dict
 
 
+def coordinates_and_timestamps_to_separation_from_bodies(coords: [astropy.coordinates.SkyCoord], timestamps: [datetime], bodies: [str], stations: [str]) -> dict:
+    """
+    compute angular distances of the given sky coordinates from the given solar system bodies at the given timestamps and stations
+    :param coords: list of SkyCoord objects to measure separation
+    :param timestamps: list of datetimes, e.g. [datetime(2020, 1, 1, 15, 0, 0), datetime(2020, 1, 1, 16, 0, 0)]
+    :param stations: list of station names, e.g. ["CS002"]
+    :param bodies: list of solar system bodies, e.g. ['sun', 'moon', 'jupiter']
+    :return A dict that maps station names to a list with a dict for each given coordinate, which maps each body body to a list of separation angles for each given timestamp.
+        E.g.
+        {"CS002":
+           [
+           {"sun": [Angle("0.7rad"), Angle("0.7rad")], "moon": [Angle("0.4rad"), Angle("0.4rad")], "jupiter": [Angle("2.7rad"), Angle("2.7rad")]},
+           {"sun": [Angle("0.8rad"), Angle("0.8rad")], "moon": [Angle("0.5rad"), Angle("0.5rad")], "jupiter": [Angle("2.6rad"), Angle("2.6rad")]}
+           ]
+        }
+        # todo: not so sure about this data structure. SkyCoord is not hashable, so we cannot use it as a key.
+        # todo: We could provide coordinates in a string format and use that as keys, or limit to a single pointing to avoid confusion.
+    """
+    return_dict = {}
+    for station in stations:
+        for coord in coords:
+            body_angles = {}
+            for body in bodies:
+                location = create_astroplan_observer_for_station(station).location
+                for timestamp in timestamps:
+                    # get body coords at timestamp
+                    body_coord = get_body(body=body, time=astropy.time.Time(timestamp), location=location)
+                    angle = coord.separation(body_coord)
+                    body_angles.setdefault(body, []).append(angle)
+            return_dict.setdefault(station, []).append(body_angles)
+    return return_dict
+
+
 def local_sidereal_time_for_utc_and_station(timestamp: datetime = None,
                                             station: str = 'CS002',
                                             field: str = 'LBA',

SAS/TMSS/src/tmss/tmssapp/views.py

@@ -15,7 +15,9 @@ from django.apps import apps
 from rest_framework.decorators import api_view
 from datetime import datetime
 import dateutil.parser
-from lofar.sas.tmss.tmss.tmssapp.conversions import local_sidereal_time_for_utc_and_station, local_sidereal_time_for_utc_and_longitude, timestamps_and_stations_to_sun_rise_and_set
+from astropy.coordinates import SkyCoord
+from astropy import units as u
+from lofar.sas.tmss.tmss.tmssapp.conversions import local_sidereal_time_for_utc_and_station, local_sidereal_time_for_utc_and_longitude, timestamps_and_stations_to_sun_rise_and_set, coordinates_and_timestamps_to_separation_from_bodies
 
 # Note: Decorate with @api_view to get this picked up by Swagger
 
@@ -169,3 +171,62 @@ def get_sun_rise_and_set(request):
 
     return JsonResponse(timestamps_and_stations_to_sun_rise_and_set(timestamps, stations))
 
+@permission_classes([AllowAny])
+@authentication_classes([AllowAny])
+@swagger_auto_schema(method='GET',
+                     responses={200: 'A JSON object with angular distances of the given sky coordinates from the given solar system bodies at the given timestamps and stations. \n'
+                                     'Outer list contains results per coordinate in given order, inner list per timestamp.'},
+                     operation_description="Get angular distances of the given sky coordinates from the given solar system bodies at all given timestamps and stations. \n\n"
+                                           "Example request: /api/util/sun_rise_and_set?coordinates=,CS005&timestamps=2020-05-01,2020-09-09T11-11-00",
+                     manual_parameters=[Parameter(name='ras', required=True, type='string', in_='query',
+                                                  description="comma-separated list of right ascensions (celestial longitudes)"),
+                                        Parameter(name='decs', required=True, type='string', in_='query',
+                                                  description="comma-separated list of declinations (celestial latitude)"),
+                                        Parameter(name='stations', required=False, type='string', in_='query',
+                                                  description="comma-separated list of station names"),
+                                        Parameter(name='timestamps', required=False, type='string', in_='query',
+                                                  description="comma-separated list of isoformat timestamps"),
+                                        Parameter(name='bodies', required=False, type='string', in_='query',
+                                                  description="comma-separated list of solar system bodies")])
+@api_view(['GET'])
+def get_angular_separation_from_bodies(request):
+    '''
+    returns angular distances of the given sky coordinates from the given astronomical objects at the given timestamps and stations
+    '''
+    stations = request.GET.get('stations', None)
+    timestamps = request.GET.get('timestamps', None)
+    ras = request.GET.get('ras', None)
+    decs = request.GET.get('decs', None)
+    bodies = request.GET.get('bodies', None)
+
+    if timestamps is None:
+        timestamps = [datetime.utcnow()]
+    else:
+        timestamps = timestamps.split(',')
+        timestamps = [dateutil.parser.parse(timestamp) for timestamp in timestamps]  #  isot to datetime
+
+    if bodies is None:
+        bodies = ['sun', 'moon', 'jupiter']
+    else:
+        bodies = bodies.split(',')
+
+    if stations is None:
+        stations = ["CS002"]
+    else:
+        stations = stations.split(',')
+
+    if ras is None or decs is None:
+        raise ValueError("Please provide celestial coordinates in radians/J2000 via the 'ras' and 'decs' the properties.")
+
+    coords = []
+    longitudes = ras.split(',')
+    latitudes = decs.split(',')
+    for ra, dec in zip(longitudes, latitudes):
+        coords.append(SkyCoord(ra=ra, dec=dec, unit=u.rad, equinox='J2000'))
+
+    sep_dict = coordinates_and_timestamps_to_separation_from_bodies(coords=coords, stations=stations, bodies=bodies, timestamps=timestamps)
+    for station, v in sep_dict.items():
+        for coord in v:
+            for object, angles in coord.items():
+                 coord[object] = [angle.rad for angle in angles]
+    return JsonResponse(sep_dict)

SAS/TMSS/src/tmss/urls.py

@@ -67,6 +67,7 @@ urlpatterns = [
     re_path('util/sun_rise_and_set/?', views.get_sun_rise_and_set, name='get_sun_rise_and_set'),
     re_path('util/utc/?', views.utc, name="system-utc"),
     re_path('util/lst/?', views.lst, name="conversion-lst"),
+    re_path('util/angular_separation_from_bodies/?', views.get_angular_separation_from_bodies, name='get_angular_separation_from_bodies'),
 ]
 
 if os.environ.get('SHOW_DJANGO_DEBUG_TOOLBAR', False):