diff --git a/fermipy/catalog.py b/fermipy/catalog.py
index ea88333a..a953b8af 100644
--- a/fermipy/catalog.py
+++ b/fermipy/catalog.py
@@ -59,6 +59,19 @@ def join_tables(left, right, key_left, key_right,
     if key_left not in cols_right:
         cols_right += [key_left]
 
+    # Fill missing (masked) values in key columns before joining (astropy >6
+    # raises TableMergeError if key columns have missing values).
+    for tbl in [left, right]:
+        if key_left in tbl.colnames:
+            col = tbl[key_left]
+            if hasattr(col, 'mask') and col.mask.any():
+                if col.dtype.kind in ['S', 'U']:
+                    tbl[key_left] = col.filled('')
+                elif col.dtype.kind in ['i']:
+                    tbl[key_left] = col.filled(0)
+                else:
+                    tbl[key_left] = col.filled(np.nan)
+
     out = join(left, right[cols_right], keys=key_left,
                join_type='left')
 
@@ -85,7 +98,7 @@ def row_to_dict(row):
     o = {}
     for colname in row.colnames:
 
-        if isinstance(row[colname], np.string_) and row[colname].dtype.kind in ['S', 'U']:
+        if isinstance(row[colname], (np.bytes_, np.str_)) and row[colname].dtype.kind in ['S', 'U']:
             o[colname] = str(row[colname])
         else:
             o[colname] = row[colname]
diff --git a/fermipy/gtanalysis.py b/fermipy/gtanalysis.py
index b0265bd3..c2c7b478 100644
--- a/fermipy/gtanalysis.py
+++ b/fermipy/gtanalysis.py
@@ -4791,7 +4791,7 @@ def _create_source(self, src):
 
         if src['SpatialType'] == 'SkyDirFunction':
             pylike_src = pyLike.PointSource(self.like.logLike.observation())
-            pylike_src.setDir(src.skydir.ra.deg, src.skydir.dec.deg, False,
+            pylike_src.setDir(float(src.skydir.ra.deg), float(src.skydir.dec.deg), False,
                               False)
         elif src['SpatialType'] == 'SpatialMap':
             filepath = str(utils.path_to_xmlpath(src['Spatial_Filename']))
@@ -4802,20 +4802,20 @@ def _create_source(self, src):
         elif src['SpatialType'] == 'RadialProfile':
             filepath = str(utils.path_to_xmlpath(src['Spatial_Filename']))
             sm = pyLike.RadialProfile(filepath)
-            sm.setCenter(src['ra'], src['dec'])
+            sm.setCenter(float(src['ra']), float(src['dec']))
             pylike_src = pyLike.DiffuseSource(sm,
                                               self.like.logLike.observation(),
                                               False)
         elif src['SpatialType'] == 'RadialGaussian':
-            sm = pyLike.RadialGaussian(src.skydir.ra.deg, src.skydir.dec.deg,
-                                       src.spatial_pars['Sigma']['value'])
+            sm = pyLike.RadialGaussian(float(src.skydir.ra.deg), float(src.skydir.dec.deg),
+                                       float(src.spatial_pars['Sigma']['value']))
             pylike_src = pyLike.DiffuseSource(sm,
                                               self.like.logLike.observation(),
                                               False)
 
         elif src['SpatialType'] == 'RadialDisk':
-            sm = pyLike.RadialDisk(src.skydir.ra.deg, src.skydir.dec.deg,
-                                   src.spatial_pars['Radius']['value'])
+            sm = pyLike.RadialDisk(float(src.skydir.ra.deg), float(src.skydir.dec.deg),
+                                   float(src.spatial_pars['Radius']['value']))
             pylike_src = pyLike.DiffuseSource(sm,
                                               self.like.logLike.observation(),
                                               False)
diff --git a/fermipy/srcmap_utils.py b/fermipy/srcmap_utils.py
index 376444bc..6fa5b44b 100644
--- a/fermipy/srcmap_utils.py
+++ b/fermipy/srcmap_utils.py
@@ -76,7 +76,7 @@ def get_offsets(self, pix):
                 idx += [0]
             else:
                 npix1 = int(self.shape[i])
-                pix0 = int(pix[i - 1]) - npix1 // 2
+                pix0 = int(pix[i - 1][0]) - npix1 // 2
                 idx += [pix0]
 
         return idx
@@ -90,7 +90,7 @@ def shift_to_coords(self, pix, fill_value=np.nan):
         for i in range(len(self.shape) - 1):
             x = self.rebin * (pix[i] - pix_offset[i + 1]
                               ) + (self.rebin - 1.0) / 2.
-            dpix[i] = x - self._pix_ref[i]
+            dpix[i] = x[0] - self._pix_ref[i]
 
         pos = [pix_offset[i] + self.shape[i] // 2
                for i in range(self.data.ndim)]