diff --git a/mintpy/objects/ionex.py b/mintpy/objects/ionex.py
index a74935668..cc8a125da 100644
--- a/mintpy/objects/ionex.py
+++ b/mintpy/objects/ionex.py
@@ -297,8 +297,6 @@ def parse_map(tec_map, key='TEC', exponent=-1):
         for line in header:
             if line.strip().endswith('# OF MAPS IN FILE'):
                 num_map = int(line.split()[0])
-            elif line.strip().endswith('DHGT'):
-                ion_hgt = float(line.split()[0])
             elif line.strip().endswith('DLAT'):
                 lat0, lat1, lat_step = [float(x) for x in line.split()[:3]]
             elif line.strip().endswith('DLON'):
@@ -382,7 +380,7 @@ def animate(*args):
     # output
     out_fig = '{}.gif'.format(os.path.abspath(tec_file))
     if save_fig:
-        print('saving animation to {}'.format(outfig))
+        print('saving animation to {}'.format(out_fig))
         ani.save(out_fig, writer='imagemagick', dpi=300)
 
     print('showing animation ...')
diff --git a/mintpy/simulation/iono.py b/mintpy/simulation/iono.py
index 2b4bce5c4..33ac32ea5 100644
--- a/mintpy/simulation/iono.py
+++ b/mintpy/simulation/iono.py
@@ -19,12 +19,7 @@
 import matplotlib.pyplot as plt
 from scipy import interpolate
 
-from mintpy.objects import ionex
-from mintpy.utils import (
-    ptime,
-    readfile,
-    utils0 as ut,
-)
+from mintpy.utils import ptime, readfile, utils0 as ut
 
 
 # constants