diff --git a/README.md b/README.md
index bc62291..d732329 100644
--- a/README.md
+++ b/README.md
@@ -493,14 +493,15 @@ Attributes: ...
     `slant_range_time` needs a spatial resolution of 0.001cm at a 1_000km distance,
     i.e. around 1e-9, well within the 1e-15 resolution of IEEE-754 float64.
 - This is a list of reference documents:
-  - Sentinel-1 document library - https://sentinels.copernicus.eu/web/sentinel/user-guides/sentinel-1-sar/document-library
+  - Sentinel-1 document library
+    - user guides: https://sentinels.copernicus.eu/web/sentinel/user-guides/sentinel-1-sar
+    - technical guides: https://sentinels.copernicus.eu/web/sentinel/technical-guides/sentinel-1-sar
   - Sentinel-1 Product Specification v3.9 07 May 2021 S1-RS-MDA-52-7441-3-9 documenting IPF 3.40 -
     https://sentinel.esa.int/documents/247904/1877131/S1-RS-MDA-52-7441-3-9-2_Sentinel-1ProductSpecification.pdf
   - Sentinel-1 Product Specification v3.7 27 February 2020 S1-RS-MDA-52-7441 documenting IPF 3.30 -
     https://sentinel.esa.int/documents/247904/1877131/Sentinel-1-Product-Specification
   - Radiometric Calibration of S-1 Level-1 Products Generated by the S-1 IPF v1.0 21/05/2015 ESA-EOPG-CSCOP-TN-0002 -
     https://sentinel.esa.int/documents/247904/685163/S1-Radiometric-Calibration-V1.0.pdf
-    https://sentinel.esa.int/documents/247904/685163/S1-Radiometric-Calibration-V1.0.pdf
 
 ## Project badges
 
diff --git a/xarray_sentinel/esa_safe.py b/xarray_sentinel/esa_safe.py
index dd5e3a8..b17039c 100644
--- a/xarray_sentinel/esa_safe.py
+++ b/xarray_sentinel/esa_safe.py
@@ -23,6 +23,7 @@
     "annotation": os.path.join(SENTINEL1_FOLDER, "s1-level-1-product.xsd"),
     "calibration": os.path.join(SENTINEL1_FOLDER, "s1-level-1-calibration.xsd"),
     "noise": os.path.join(SENTINEL1_FOLDER, "s1-level-1-noise.xsd"),
+    "aux_orbit": os.path.join(SENTINEL1_FOLDER, "my-schema_orb.xsd"),
 }
 
 SENTINEL2_NAMESPACES = {
diff --git a/xarray_sentinel/resources/sentinel1/my-schema_orb.xsd b/xarray_sentinel/resources/sentinel1/my-schema_orb.xsd
new file mode 100644
index 0000000..0a3d507
--- /dev/null
+++ b/xarray_sentinel/resources/sentinel1/my-schema_orb.xsd
@@ -0,0 +1,132 @@
+<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
+  <xs:element name="Earth_Explorer_File">
+    <xs:complexType>
+      <xs:sequence>
+        <xs:element name="Earth_Explorer_Header">
+          <xs:complexType>
+            <xs:sequence>
+              <xs:element name="Fixed_Header">
+                <xs:complexType>
+                  <xs:sequence>
+                    <xs:element type="xs:string" name="File_Name"/>
+                    <xs:element type="xs:string" name="File_Description"/>
+                    <xs:element type="xs:string" name="Notes"/>
+                    <xs:element type="xs:string" name="Mission"/>
+                    <xs:element type="xs:string" name="File_Class"/>
+                    <xs:element type="xs:string" name="File_Type"/>
+                    <xs:element name="Validity_Period">
+                      <xs:complexType>
+                        <xs:sequence>
+                          <xs:element type="xs:string" name="Validity_Start"/>
+                          <xs:element type="xs:string" name="Validity_Stop"/>
+                        </xs:sequence>
+                      </xs:complexType>
+                    </xs:element>
+                    <xs:element type="xs:byte" name="File_Version"/>
+                    <xs:element name="Source">
+                      <xs:complexType>
+                        <xs:sequence>
+                          <xs:element type="xs:string" name="System"/>
+                          <xs:element type="xs:string" name="Creator"/>
+                          <xs:element type="xs:string" name="Creator_Version"/>
+                          <xs:element type="xs:string" name="Creation_Date"/>
+                        </xs:sequence>
+                      </xs:complexType>
+                    </xs:element>
+                  </xs:sequence>
+                </xs:complexType>
+              </xs:element>
+              <xs:element name="Variable_Header">
+                <xs:complexType>
+                  <xs:sequence>
+                    <xs:element type="xs:string" name="Ref_Frame"/>
+                    <xs:element type="xs:string" name="Time_Reference"/>
+                  </xs:sequence>
+                </xs:complexType>
+              </xs:element>
+            </xs:sequence>
+          </xs:complexType>
+        </xs:element>
+        <xs:element name="Data_Block">
+          <xs:complexType>
+            <xs:sequence>
+              <xs:element name="List_of_OSVs">
+                <xs:complexType>
+                  <xs:sequence>
+                    <xs:element name="OSV" maxOccurs="unbounded" minOccurs="0">
+                      <xs:complexType>
+                        <xs:sequence>
+                          <xs:element type="xs:string" name="TAI"/>
+                          <xs:element type="xs:string" name="UTC"/>
+                          <xs:element type="xs:string" name="UT1"/>
+                          <xs:element type="xs:short" name="Absolute_Orbit"/>
+                          <xs:element name="X">
+                            <xs:complexType>
+                              <xs:simpleContent>
+                                <xs:extension base="xs:float">
+                                  <xs:attribute type="xs:string" name="unit" use="optional"/>
+                                </xs:extension>
+                              </xs:simpleContent>
+                            </xs:complexType>
+                          </xs:element>
+                          <xs:element name="Y">
+                            <xs:complexType>
+                              <xs:simpleContent>
+                                <xs:extension base="xs:float">
+                                  <xs:attribute type="xs:string" name="unit" use="optional"/>
+                                </xs:extension>
+                              </xs:simpleContent>
+                            </xs:complexType>
+                          </xs:element>
+                          <xs:element name="Z">
+                            <xs:complexType>
+                              <xs:simpleContent>
+                                <xs:extension base="xs:float">
+                                  <xs:attribute type="xs:string" name="unit" use="optional"/>
+                                </xs:extension>
+                              </xs:simpleContent>
+                            </xs:complexType>
+                          </xs:element>
+                          <xs:element name="VX">
+                            <xs:complexType>
+                              <xs:simpleContent>
+                                <xs:extension base="xs:float">
+                                  <xs:attribute type="xs:string" name="unit" use="optional"/>
+                                </xs:extension>
+                              </xs:simpleContent>
+                            </xs:complexType>
+                          </xs:element>
+                          <xs:element name="VY">
+                            <xs:complexType>
+                              <xs:simpleContent>
+                                <xs:extension base="xs:float">
+                                  <xs:attribute type="xs:string" name="unit" use="optional"/>
+                                </xs:extension>
+                              </xs:simpleContent>
+                            </xs:complexType>
+                          </xs:element>
+                          <xs:element name="VZ">
+                            <xs:complexType>
+                              <xs:simpleContent>
+                                <xs:extension base="xs:float">
+                                  <xs:attribute type="xs:string" name="unit" use="optional"/>
+                                </xs:extension>
+                              </xs:simpleContent>
+                            </xs:complexType>
+                          </xs:element>
+                          <xs:element type="xs:string" name="Quality"/>
+                        </xs:sequence>
+                      </xs:complexType>
+                    </xs:element>
+                  </xs:sequence>
+                  <xs:attribute type="xs:short" name="count"/>
+                </xs:complexType>
+              </xs:element>
+            </xs:sequence>
+            <xs:attribute type="xs:string" name="type"/>
+          </xs:complexType>
+        </xs:element>
+      </xs:sequence>
+    </xs:complexType>
+  </xs:element>
+</xs:schema>
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