diff --git a/coolest/template/classes/likelihood.py b/coolest/template/classes/likelihood.py
index ce74d0a..90530b9 100644
--- a/coolest/template/classes/likelihood.py
+++ b/coolest/template/classes/likelihood.py
@@ -72,9 +72,9 @@ def check_consistency_with_observation(self, observation):
         width  = abs(self.mask.field_of_view_x[1] - self.mask.field_of_view_x[0])
         height = abs(self.mask.field_of_view_y[1] - self.mask.field_of_view_y[0])
         num_pix_ra = round(width / observation.pixels.pixel_size)
-        error_message_ra = f"Field-of-view along RA is inconsistent (data: {num_pix_ra}, likelihood mask: {self.mask.num_pix_x})."
+        error_message_ra = f"Number of pixels along x is inconsistent (data: {num_pix_ra}, likelihood mask: {self.mask.num_pix_x})."
         assert self.mask.num_pix_x  == num_pix_ra, error_message_ra
         num_pix_dec = round(height / observation.pixels.pixel_size)
-        error_message_dec = f"Field-of-view along Dec is inconsistent (data: {num_pix_dec}, likelihood mask: {self.mask.num_pix_y})."
+        error_message_dec = f"Number of pixels along y is inconsistent (data: {num_pix_dec}, likelihood mask: {self.mask.num_pix_y})."
         assert self.mask.num_pix_y  == num_pix_dec, error_message_dec
         # TODO: check pixel size value?
diff --git a/coolest/template/classes/observation.py b/coolest/template/classes/observation.py
index cd47bd5..ff5abef 100644
--- a/coolest/template/classes/observation.py
+++ b/coolest/template/classes/observation.py
@@ -54,10 +54,10 @@ def check_consistency_with_instrument(self, instrument):
         width  = abs(self.pixels.field_of_view_x[1] - self.pixels.field_of_view_x[0])
         height = abs(self.pixels.field_of_view_y[1] - self.pixels.field_of_view_y[0])
         num_pix_ra = round(width / instrument.pixel_size)
-        error_message_ra = f"Field-of-view along RA is inconsistent (data: {self.pixels.num_pix_x}, instrument: {num_pix_ra})."
+        error_message_ra = f"Number of pixels along x is inconsistent (data: {self.pixels.num_pix_x}, instrument: {num_pix_ra})."
         assert self.pixels.num_pix_x  == num_pix_ra, error_message_ra
         num_pix_dec = round(height / instrument.pixel_size)
-        error_message_dec = f"Field-of-view along Dec is inconsistent (data: {self.pixels.num_pix_y}, instrument: {num_pix_dec})."
+        error_message_dec = f"Number of pixels along y is inconsistent (data: {self.pixels.num_pix_y}, instrument: {num_pix_dec})."
         assert self.pixels.num_pix_y  == num_pix_dec, error_message_dec
         # TODO: check pixel size value?
 
diff --git a/coolest/template/json.py b/coolest/template/json.py
index 558f028..d671012 100644
--- a/coolest/template/json.py
+++ b/coolest/template/json.py
@@ -88,7 +88,7 @@ def dump_jsonpickle(self):
         with open(json_path, 'w') as f:
             f.write(result)
 
-    def load(self, skip_jsonpickle=False, verbose=True):
+    def load(self, skip_jsonpickle=False, validate=True, verbose=True):
         """Read the JSON template file and build up the corresponding COOLEST object.
         It will first try to load the '_pyAPI' template if it exists using `jsonpickle`, 
         otherwise it will fall back to reading the pure json template.
@@ -114,11 +114,11 @@ def load(self, skip_jsonpickle=False, verbose=True):
         else:
             if verbose:
                 print(f"Template file '{jsonpickle_path}' not found, now trying to read '{json_path}'.")
-            instance = self.load_simple(json_path, as_object=True)
+            instance = self.load_simple(json_path, as_object=True, validate=validate)
         assert isinstance(instance, COOLEST)
         return instance
 
-    def load_simple(self, json_path, as_object=True):
+    def load_simple(self, json_path, as_object=True, validate=True):
         """Read the JSON template file and build up the corresponding COOLEST object. 
 
         Parameters
@@ -137,7 +137,7 @@ def load_simple(self, json_path, as_object=True):
             content = json.loads(f.read())
         if not as_object:
             return content  # dictionary
-        return self._json_to_coolest(content)  # COOLEST object
+        return self._json_to_coolest(content, validate)  # COOLEST object
 
     def load_jsonpickle(self, jsonpickle_path):
         """Read the JSON template file and build up the corresponding COOLEST object
@@ -157,7 +157,7 @@ def load_jsonpickle(self, jsonpickle_path):
             content = jsonpickle.decode(f.read())
         return content  # COOLEST object
 
-    def _json_to_coolest(self, json_content):
+    def _json_to_coolest(self, json_content, validate):
         """Creates from scratch a COOLEST instance based on the content of a JSON
         file, given as a nested dictionnary.
 
@@ -208,7 +208,8 @@ def _json_to_coolest(self, json_content):
                           metadata=metadata)
 
         # check consistency across the whole coolest object
-        self._validate_global(coolest)
+        if validate:
+            self._validate_global(coolest)
         return coolest
 
     @staticmethod
diff --git a/test/template/json_test.py b/test/template/json_test.py
index 1a3ed5f..d593ecb 100644
--- a/test/template/json_test.py
+++ b/test/template/json_test.py
@@ -119,7 +119,7 @@ def test_dump_and_read(self):
         # and btw we also instantiate another JSONSerializer as a test
         serializer_2 = JSONSerializer(template_path, obj=None,
                                       check_external_files=self.check_files)
-        coolest_3 = serializer_2.load(skip_jsonpickle=True)
+        coolest_3 = serializer_2.load(skip_jsonpickle=True, validate=False)  # no validation as it is a dummy json file
         assert isinstance(coolest_3, COOLEST)
 
         # test that the content of the new json file is *exactly* the same as the original one