to_ephem was in the wrong spot

Author: mkelley

sbpy/dynamics/state.py

@@ -294,15 +294,21 @@ def to_skycoord(self) -> SkyCoord:
         else:
             return SkyCoord(self._data, obstime=self.t, representation_type="cartesian")
 
-    def to_ephem(self, observer: StateType | None = None) -> Ephem:
+    def to_ephem(
+        self, observer: StateType | None = None, coords: SkyCoord | None = None
+    ) -> Ephem:
         r"""Convert to an sbpy ephemeris object.
 
 
         Parameters
         ----------
         observer : `State`, optional
-            Calculate RA/longitude, Dec/latitude, distance, etc for this
-            observer.
+            Include this observer in the metadata.  If ``coords`` is ``None``,
+            then also calculate RA/longitude, Dec/latitude, distance, etc for
+            this observer.
+
+        coords : `~astropy.coordinates.SkyCoord`, optional
+            Include these observer-based coordinates in the result.
 
 
         Returns
@@ -364,20 +370,23 @@ def to_ephem(self, observer: StateType | None = None) -> Ephem:
 
         if observer is not None:
             meta["observer"] = {
-                "r": self.observer.r,
-                "v": self.observer.v,
-                "t": self.observer.t,
-                "frame": self.observer.frame,
+                "r": observer.r,
+                "v": observer.v,
+                "t": observer.t,
+                "frame": observer.frame,
             }
 
-            coords = observer.observe(self)
+            if coords is None:
+                coords = observer.observe(self)
 
-            # use SkyCoords's to_table() method, which will account for when
+            # use SkyCoord's to_table() method, which will account for when
             # RA/Dec vs lon/lat are used.
             tab = coords.to_table()
 
-            # convert SkyCoords's column names to Ephem's field names
-            skycoords_to_ephem = {
+            # convert SkyCoord's column names to Ephem's field names
+            skycoord_to_ephem = {
+                "pm_ra": "ra_rate",
+                "pm_lon": "lon_rate",
                 "pm_ra_cosdec": "ra*cos(dec)_rate",
                 "pm_lon_coslat": "lon*cos(lat)_rate",
                 "pm_dec": "dec_rate",
@@ -386,7 +395,7 @@ def to_ephem(self, observer: StateType | None = None) -> Ephem:
                 "radial_velocity": "deltadot",
             }
             for col in tab.colnames:
-                field = skycoords_to_ephem.get(col, col)
+                field = skycoord_to_ephem.get(col, col)
                 data[field] = tab[col]
 
         return Ephem.from_dict(data, meta=meta)

sbpy/dynamics/syndynes.py

@@ -133,7 +133,7 @@ def to_ephem(self) -> Ephem:
 
         """
 
-        eph = super().to_ephem(observer=self.observer)
+        eph = super().to_ephem(observer=self.observer, coords=self.coords)
 
         eph["beta_rad"] = self.betas
         eph["age"] = self.ages

sbpy/dynamics/tests/test_state.py

@@ -562,7 +562,7 @@ def test_from_ephem(self):
             with pytest.raises(ValueError):
                 State.from_ephem(incomplete)
 
-    def test_to_ephm(self):
+    def test_to_ephem(self):
         r = np.arange(1, 7).reshape([2, 3]) * u.au
         v = r.value / 10 * u.km / u.s
         t = [0, 1] * u.day
@@ -582,3 +582,16 @@ def test_to_ephm(self):
         eph = state.to_ephem()
         assert np.allclose(eph["date"].mjd, [51544.0, 51545.0])
         assert isinstance(eph.meta["frame"], ICRS)
+
+        # observer with an observer
+        observer = State(
+            [0, 0, 1] * u.au, [0, 0, 0] * u.km / u.s, state.t[0], frame="icrs"
+        )
+        eph = state.to_ephem(observer=observer)
+        coords = observer.observe(state)
+        assert all(eph["ra"] == coords.ra)
+        assert all(eph["dec"] == coords.dec)
+        assert all(eph["ra_rate"] == coords.pm_ra)
+        assert all(eph["dec_rate"] == coords.pm_dec)
+        assert all(eph["delta"] == coords.distance)
+        assert all(eph["deltadot"] == coords.radial_velocity)