diff --git a/corsika/modules/ObservationPlane.hpp b/corsika/modules/ObservationPlane.hpp
index aec2c0086555563d1b9718a9387bbac9733c8d9f..f37591c6ec9e76e959f5bf06ff7e19dc5d5e01d9 100644
--- a/corsika/modules/ObservationPlane.hpp
+++ b/corsika/modules/ObservationPlane.hpp
@@ -15,9 +15,6 @@
 #include <corsika/setup/SetupTrajectory.hpp>
 #include <corsika/modules/writers/ObservationPlaneWriterParquet.hpp>
 
-#include <fstream>
-#include <string>
-
 namespace corsika {
 
   /**
@@ -42,6 +39,7 @@ namespace corsika {
     void reset();
     HEPEnergyType getEnergyGround() const { return energy_ground_; }
     YAML::Node getConfig() const;
+
   private:
     Plane const plane_;
     bool const deleteOnHit_;
diff --git a/corsika/modules/writers/ObservationPlaneWriterParquet.hpp b/corsika/modules/writers/ObservationPlaneWriterParquet.hpp
index cda8b8fb5119a116e9d1516aca8182c34b83158d..240b808e1f5aba8514f9e1b31badf95e31a74684 100644
--- a/corsika/modules/writers/ObservationPlaneWriterParquet.hpp
+++ b/corsika/modules/writers/ObservationPlaneWriterParquet.hpp
@@ -21,7 +21,7 @@ namespace corsika {
 
   public:
     /**
-     * Write an observation plane to a directory.
+     * Construct an ObservationPlane.
      *
      * @param name    The name of this output.
      */
diff --git a/corsika/output/ParquetStreamer.hpp b/corsika/output/ParquetStreamer.hpp
index 3e5c2f1c0dbbcffc7cbe2dae73d4c66b5ec76842..240e2af0f9f3c8538de3288ba9b021b95f1e3577 100644
--- a/corsika/output/ParquetStreamer.hpp
+++ b/corsika/output/ParquetStreamer.hpp
@@ -1,3 +1,4 @@
+
 /*
  * (c) Copyright 2021 CORSIKA Project, corsika-project@lists.kit.edu
  *
@@ -26,11 +27,11 @@ namespace corsika {
   class ParquetStreamer {
 
   protected:
-    std::shared_ptr<parquet::StreamWriter> writer_; ///< The stream writer to 'outfile'
-    parquet::WriterProperties::Builder builder_;    ///< The writer properties builder.
-    parquet::schema::NodeVector fields_;            ///< The fields in this file.
+    parquet::WriterProperties::Builder builder_; ///< The writer properties builder.
+    parquet::schema::NodeVector fields_;         ///< The fields in this file.
     std::shared_ptr<parquet::schema::GroupNode> schema_;   ///< The schema for this file.
     std::shared_ptr<arrow::io::FileOutputStream> outfile_; ///< The output file.
+    std::shared_ptr<parquet::StreamWriter> writer_; ///< The stream writer to 'outfile'
 
   public:
     /**
@@ -59,6 +60,11 @@ namespace corsika {
      */
     void closeStreamer();
 
+    /**
+     * Return a reference to the underlying writer.
+     */
+    std::shared_ptr<parquet::StreamWriter> getWriter();
+
   }; // class ParquetHelper
 } // namespace corsika
 
diff --git a/python/corsika/io/outputs/observation_plane.py b/python/corsika/io/outputs/observation_plane.py
index 3b2680e17f6e98c395d94496f870c18fb57e427a..271d145b4f076f1c7d747d6cc5e05b4a183d3655 100644
--- a/python/corsika/io/outputs/observation_plane.py
+++ b/python/corsika/io/outputs/observation_plane.py
@@ -9,7 +9,7 @@
 """
 import logging
 import os.path as op
-from typing import Any, Dict
+from typing import Any
 
 import pyarrow.parquet as pq