added tests in uvdata.check for non-zero uvw of autocorr and near-zer…

…o uvw of cross corr

pyuvdata/tests/test_uvdata.py

@@ -217,6 +217,22 @@ def test_check(self):
                                                 == self.uv_object.ant_2_array)[0])
         nt.assert_true(self.uv_object.check())
 
+        # test auto and cross corr uvw_array
+        uvd = UVData()
+        uvd.read_miriad(os.path.join(DATA_PATH, "zen.2457698.40355.xx.HH.uvcA"))
+        autos = np.isclose(uvd.ant_1_array - uvd.ant_2_array, 0.0)
+        auto_inds = np.where(autos)[0]
+        cross_inds = np.where(~autos)[0]
+
+        # make auto have non-zero uvw coords, assert ValueError
+        uvd.uvw_array[auto_inds[0], 0] = 0.1
+        nt.assert_raises(ValueError, uvd.check)
+
+        # make cross have |uvw| zero, assert ValueError
+        uvd.read_miriad(os.path.join(DATA_PATH, "zen.2457698.40355.xx.HH.uvcA"))
+        uvd.uvw_array[cross_inds[0]][:] = 0.0
+        nt.assert_raises(ValueError, uvd.check)
+
     def test_nants_data_telescope(self):
         self.uv_object.Nants_data = self.uv_object.Nants_telescope - 1
         nt.assert_true(self.uv_object.check)

pyuvdata/uvdata.py

@@ -97,7 +97,7 @@ def __init__(self):
         self._uvw_array = uvp.UVParameter('uvw_array', description=desc,
                                           form=('Nblts', 3),
                                           expected_type=np.float,
-                                          acceptable_range=(0.0, 1e8), tols=.001)
+                                          acceptable_range=(0, 1e8), tols=1e-3)
 
         desc = ('Array of times, center of integration, shape (Nblts), '
                 'units Julian Date')
@@ -384,6 +384,15 @@ def check(self, check_extra=True, run_check_acceptability=True):
                               'which will raise an error when writing uvfits or '
                               'miriad file types'.format(key=key))
 
+        # check auto and cross-corrs have sensible uvws
+        autos = np.isclose(self.ant_1_array - self.ant_2_array, 0.0)
+        if not np.all(np.isclose(self.uvw_array[autos], 0.0)):
+            raise ValueError("Some auto-correlations have non-zero "
+                             "uvw_array coordinates.")
+        if np.any(np.isclose([np.linalg.norm(uvw) for uvw in self.uvw_array[~autos]], 0.0)):
+            raise ValueError("Some cross-correlations have near-zero "
+                             "uvw_array magnitudes.")
+
         return True
 
     def set_drift(self):