diff --git a/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py b/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py
index ac3133d845aaa2c0db3d8d9ee5d87c24fb9f4bc5..f77a87333fc17ba7d340eda4bacf4037f81a6dc5 100644
--- a/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py
+++ b/CAL/CalibrationCommon/lib/datacontainers/holography_dataset.py
@@ -385,7 +385,7 @@ class HolographyDataset():
             raise ValueError('Multiple RCUs mode are not supported')
 
         if len(source_position) == 1:
-            self.source_position = source_position.pop()
+            self.source_position = numpy.array(source_position.pop(), dtype=HDS_coordinate_type)
         else:
             logger.error('Multiple source positions are not supported: %s', source_position)
             raise ValueError('Multiple source positions are not supported')
@@ -592,8 +592,7 @@ class HolographyDataset():
             f.attrs[HDS_TARGET_STATION_POSITION] = self.target_station_position
             f.attrs[HDS_SOURCE_NAME] = self.source_name
 
-            f.attrs[HDS_SOURCE_POSITION] = numpy.array(self.source_position,
-                                                       dtype=HDS_coordinate_type)
+            f.attrs[HDS_SOURCE_POSITION] = self.source_position
             f.attrs[HDS_OBSERVATION_TIME] = numpy.array([self.start_time, self.end_time])
             f.attrs[HDS_ROTATION_MATRIX] = self.rotation_matrix
             f.attrs[HDS_ANTENNA_FIELD_POSITION] = self.antenna_field_position