Update some inaccurate comments noted in review

stellarphot/core.py

@@ -809,7 +809,8 @@ def _tidy_vizier_catalog(data, mag_column_regex, color_column_regex):
         """
         Transform a Vizier catalog with magnitudes into tidy structure. Or
         at least tidier -- this only handles changing magnitude and color
-        columns into tidy format.
+        columns into tidy format. In that format each row is a single
+        observation of a single object in a single passband.
 
         Parameters
         ----------
@@ -1071,8 +1072,8 @@ def vsx_vizier(header_or_center,
                clip_by_frame=False,
                padding=100):
     """
-    Return the items from APASS DR9 that are within the search radius and
-    (optionally) within the field of view of a frame.
+    Return the items from the copy of VSX on Vizier that are within the search
+    radius and (optionally) within the field of view of a frame.
 
     Parameters
     ----------

stellarphot/tests/test_core.py

@@ -162,8 +162,8 @@ def test_bet_clean_criteria_none_removed():
                              ('=-1', 1)])
 def test_bet_clean_criteria_some_removed(condition, input_row):
     """
-    Try a few filters which remove the second row and check that it is
-    removed.
+    Try a few filters which leave only one row and make sure that row is
+    returned.
     """
     inp = a_table()
     criteria = {'b': condition}