diff --git a/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py b/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py
index 4ae665d458d2930ec211491567fb31b6c338889a..7e4e224c555575c1ff45b085d08d77f7c7e61fb7 100644
--- a/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py
+++ b/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py
@@ -293,10 +293,10 @@ class HolographyDataset():
         logger.info("Creating a holography data set for station \"%s\"...", station_name)
         try:
             logger.debug('collecting preliminary information')
-            self.__collect_preliminary_information(station_name, list_of_hbs_ms_tuples)
+            self._collect_preliminary_information(station_name, list_of_hbs_ms_tuples)
             logger.debug('collected preliminary information')
             logger.debug('reading data')
-            self.__read_data(station_name, list_of_hbs_ms_tuples)
+            self._read_data(station_name, list_of_hbs_ms_tuples)
             logger.debug('read data')
             self._central_beamlets = self.find_central_beamlets(self._source_position, self._ra_dec,
                                                                 self._frequencies, self._beamlets)
@@ -349,7 +349,7 @@ class HolographyDataset():
                 raise ValueError(text)
         return minimal_distance_per_frequency
 
-    def __read_data(self, station_name, list_of_hbs_ms_tuples):
+    def _read_data(self, station_name, list_of_hbs_ms_tuples):
         """
 
         :param station_name:
@@ -391,7 +391,7 @@ class HolographyDataset():
                         self.data[reference_station][frequency_string][beamlet_string] = \
                             cross_correlation[reference_station_index, :]
 
-    def __collect_preliminary_information(self, station_name, list_of_hbs_ho_tuples):
+    def _collect_preliminary_information(self, station_name, list_of_hbs_ho_tuples):
         """
         This routines reads both the holography beam specifications files and the holography
         observation to gather the list of rcus, the mode, the target station name and position,