Revert "Initalize CircularAperture from coma equivalent radius."

This reverts commit cbb0156.

docs/sbpy/activity/index.rst

@@ -16,7 +16,7 @@ Introduction
 Apertures
 ---------
 
-Four photometric aperture classes are defined, primarily for use with cometary comae:
+Four photometric apertures are defined:
 
   * `~sbpy.activity.CircularAperture`: a circle,
   * `~sbpy.activity.AnnularAperture`: an annulus,
@@ -48,10 +48,6 @@ Ideal comae (constant production rate, free-expansion, infinite lifetime) have *
   >>> sba.CircularAperture(ap.coma_equivalent_radius())  # doctest: +FLOAT_CMP
   <CircularAperture: radius 1669.4204086589311 km>
 
-Through the ``coma_equivalent_radius()`` method, all apertures may be used to initialize a ``CircularAperture`` instance using the :func:`~sbpy.activity.CircularAperture.from_coma_equivalent` method:
-
-  >>> sba.CircularAperture.from_coma_equivalent(ap)
-  <CircularAperture: radius 1669.4204086589311 km>
 
 Reference/API
 -------------

sbpy/activity/core.py

@@ -134,25 +134,6 @@ def coma_equivalent_radius(self):
         return self.radius
     coma_equivalent_radius.__doc__ = Aperture.coma_equivalent_radius.__doc__
 
-    @classmethod
-    def from_coma_equivalent(cls, aperture):
-        """Initialize based on coma equivalent radius.
-
-
-        Parameters
-        ----------
-        aperture : `Aperture` or `~sbpy.units.Quantity`
-            Another aperture or a radius.
-
-        """
-
-        if isinstance(aperture, Aperture):
-            radius = aperture.coma_equivalent_radius()
-        else:
-            radius = u.Quantity(aperture)
-
-        return cls(radius)
-
 
 class AnnularAperture(Aperture):
     """Annular aperture projected at the distance of the target.

sbpy/activity/tests/test_core.py

@@ -35,17 +35,6 @@ def test_as_angle(self):
         angle = r.to('arcsec', sbu.projected_size(eph))
         assert np.isclose(aper.as_angle(eph).dim.value, angle.value)
 
-    def test_from_coma_equivalent(self):
-        # test initialization from another aperture
-        shape = [1, 2] * u.arcsec
-        an_aper = AnnularAperture(shape)
-        circ_aper = CircularAperture.from_coma_equivalent(an_aper)
-        assert circ_aper.dim == 1 * u.arcsec
-
-        # test initialization from a radius
-        circ_aper = CircularAperture.from_coma_equivalent(1 * u.arcsec)
-        assert circ_aper.dim == 1 * u.arcsec
-
 
 class TestAnnularAperture:
     def test_str(self):