diff --git a/CHANGELOG b/CHANGELOG
index 3e872815098fb0353200afb194b6fe23bd91e37d..ea3df7eb64e79b3fcc4e2ff1d23e26511e2e98d8 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -588,3 +588,8 @@ Added missing dependency for STAC inquiry.
 
 Fixed definition of bounding box for global selection.
   src/cso/cso_dataspace.py
+
+Option to initialize empty listing with extra columns.
+  src/cso/cso_file.py
+  src/cso/cso_colhub.py
+
diff --git a/doc/source/history.rst b/doc/source/history.rst
index 6db139820c4cfc71359e5460fda66db5d3f9c828..ccdd38cbc56cc0e2a533a48f4ccde102165d8c68 100644
--- a/doc/source/history.rst
+++ b/doc/source/history.rst
@@ -127,6 +127,11 @@ A summary of the versions and changes.
   
 * | *v2.15*
   | Updates for access to Copernicus DataSpace: use STAC API to inquire, and download from S3 buckets.
+  | *(2026-03)*
+
+* | *vx.y*
+  | Removed support for SO\ :sub:`2` COBRA product as this has become operational.
+  | *(2026-04)*
 
 
 To be done
diff --git a/doc/source/s5p-so2.rst b/doc/source/s5p-so2.rst
index 90761ec29f06d49f8a79324bf04effb505f79ce1..c519d8d615ae43700d3d1781d4444528be080051 100644
--- a/doc/source/s5p-so2.rst
+++ b/doc/source/s5p-so2.rst
@@ -10,7 +10,7 @@ This chapter describes the tasks performed for processing Sentinel-5p SO\ :sub:`
 from the operational processing.
 
 Up to March 2026, the current operational product was available as SO2-COBRA (Theys et al., 2021)
-from the `S5P-PAL Data Portal <https://data-portal.s5p-pal.com/>`_ .
+from the `S5P-PAL Data Portal <https://data-portal.s5p-pal.com/>`_.
 
 
 Product description
diff --git a/src/cso/cso_colhub.py b/src/cso/cso_colhub.py
index 1e0a4a43f45da6fdf533f9d293c35ee4debc40f8..de30345a9b41c6f57c4d7aaaa9e300adac64a028 100644
--- a/src/cso/cso_colhub.py
+++ b/src/cso/cso_colhub.py
@@ -27,6 +27,9 @@
 # 2025-09, Arjo Segers
 #   Added "CSO_ColHubMirror_Cleanup" class.
 #
+# 2026-04, Arjo Segers
+#   Initialize columns of listing file.
+#
 
 ########################################################################
 ###
@@ -180,8 +183,9 @@ class CSO_ColHubMirror_Inquire(utopya.UtopyaRc):
             # info ..
             logging.info(f"{indent}create %s ..." % lst_file)
 
-            # initiallize for (re)creation:
-            listing = cso_file.CSO_Listing()
+            # initiallize for (re)creation,
+            # define extra columns to ensure correct content even for empty files:
+            listing = cso_file.CSO_Listing( columns=["orbit","processing","collection","processor_version","href"] )
 
             # archive directories
             archive_dirs = self.GetSetting("dir").split()
@@ -282,6 +286,8 @@ class CSO_ColHubMirror_Inquire(utopya.UtopyaRc):
 
             # endfor # archive_dir
 
+            # info ...
+            logging.warning(f"{indent}save ...")
             # sort:
             listing.Sort(by="orbit")
             # save:
diff --git a/src/cso/cso_dataspace.py b/src/cso/cso_dataspace.py
index bd7e7234c1ecb8d9f99a08815c540db33f43e2f4..5209280b823f4d04729ac660b5d461abacb0f8b6 100644
--- a/src/cso/cso_dataspace.py
+++ b/src/cso/cso_dataspace.py
@@ -53,7 +53,7 @@
 #
 # 2026-04, Arjo Segers
 #   Fixed definition of bounding box for global selection.
-#   Added delays to avoid rate limit errors from STAC catalogue inquiry.
+#   Added increasing delays to avoid rate limit errors from STAC catalogue inquiry.
 #
 
 
@@ -340,6 +340,7 @@ class CSO_DataSpace_Inquire(utopya.UtopyaRc):
             maxtry = 10
             ntry = 1
             nsec_wait = 5
+            nsec_wait_max = 600
             # loop until success or too many errors:
             while True:
                 # until success:
@@ -429,6 +430,8 @@ class CSO_DataSpace_Inquire(utopya.UtopyaRc):
                         time.sleep(nsec_wait)
                         ntry += 1
                         logging.warning(f"{indent}    attempt {ntry} / {maxtry} ...")
+                        # next time, wait a bit longer, but not too long ...
+                        nsec_wait = min(nsec_wait * 2, nsec_wait_max)
                     # endif
                 # endtry
 
diff --git a/src/cso/cso_file.py b/src/cso/cso_file.py
index b638e39e3631c8467eb34d8336e49fb7a02fce77..1f121f50ccae4164ab790accc23a838050e27560 100644
--- a/src/cso/cso_file.py
+++ b/src/cso/cso_file.py
@@ -65,6 +65,9 @@
 #   Updated use of Dataset.dims following deprication warning.
 #   Removed whitespace from template replacement.
 #
+# 2026-04, Arjo Segers
+#   Added optional "columns" argument to initialize empty listing object.
+#
 
 ########################################################################
 ###
@@ -1306,10 +1309,11 @@ class CSO_Listing(object):
     Optional arguments:
 
     * ``filename`` : listing file read into table
+    * ``columns`` : extra columns that will be created if an empty listing is initialized
 
     """
 
-    def __init__(self, filename=None, indent=""):
+    def __init__(self, filename=None, columns=[], indent=""):
         """
         Initialize empty table or read existing.
         """
@@ -1360,7 +1364,7 @@ class CSO_Listing(object):
             self.dirname = os.curdir
 
             # new empty table:
-            self.df = pandas.DataFrame(columns=["start_time", "end_time"])
+            self.df = pandas.DataFrame(columns=["start_time", "end_time"] + columns)
 
         # endif