@@ -767,7 +767,7 @@ def __init__(self,
                  time=None, antenna1=None, antenna2=None, vis=None,
                  weight=None, imaging_weight=None, integration_time=None,
                  polarisation_frame=PolarisationFrame('stokesI'), cindex=None,
-                 blockvis=None):
+                 blockvis=None, source='anonymous'):
         """Visibility
 
         :param data:
@@ -786,6 +786,7 @@ def __init__(self,
         :param polarisation_frame:
         :param cindex:
         :param blockvis:
+        :param source:
         """
         if data is None and vis is not None:
             if imaging_weight is None:
@@ -829,6 +830,7 @@ def __init__(self,
         self.configuration = configuration  # Antenna/station configuration
         self.polarisation_frame = polarisation_frame
         self.frequency_map = None
+        self.source = source
 
     def __str__(self):
         """Default printer for Visibility
@@ -837,6 +839,7 @@ def __str__(self):
         ufrequency = numpy.unique(self.frequency)
         uchannel_bandwidth = numpy.unique(self.channel_bandwidth)
         s = "Visibility:\n"
+        s += "\tSource: %s\n" % source
         s += "\tNumber of visibilities: %s\n" % self.nvis
         s += "\tNumber of channels: %d\n" % len(ufrequency)
         s += "\tFrequency: %s\n" % ufrequency
@@ -1004,6 +1007,7 @@ def __str__(self):
         """
         s = "BlockVisibility:\n"
         s += "\tSource %s\n" % self.source
+        s += "\tPhasecentre: %s\n" % self.phasecentre
         s += "\tNumber of visibilities: %s\n" % self.nvis
         s += "\tNumber of integrations: %s\n" % len(self.time)
         s += "\tVisibility shape: %s\n" % str(self.vis.shape)
@@ -1012,7 +1016,6 @@ def __str__(self):
         s += "\tChannel bandwidth: %s\n" % self.channel_bandwidth
         s += "\tNumber of polarisations: %s\n" % self.npol
         s += "\tPolarisation Frame: %s\n" % self.polarisation_frame.type
-        s += "\tPhasecentre: %s\n" % self.phasecentre
         s += "\tConfiguration: %s\n" % self.configuration.name
         s += "\tMetadata: %s\n" % self.meta
 
 
@@ -41,7 +41,8 @@ def append_visibility(vis: Union[Visibility, BlockVisibility], othervis: Union[V
     assert abs(vis.phasecentre.dec.value - othervis.phasecentre.dec.value) < 1e-15, "Declinations differ"
     assert vis.phasecentre.separation(othervis.phasecentre).value < 1e-15, "Phasecentres differ"
     assert vis.source == othervis.source, "Not the same source"
-    assert numpy.testing.assert_array_almost_equal_nulp(vis.frequency, othervis.frequency, nulp=12)
+    if isinstance(vis, BlockVisibility): 
+        assert numpy.testing.assert_array_almost_equal_nulp(vis.frequency, othervis.frequency, nulp=12)
 
     vis.data = numpy.hstack((vis.data, othervis.data))
     return vis