From 4e5d48e5ee6a9b950bbd91f076c68d82c6436691 Mon Sep 17 00:00:00 2001
From: arthomnix <arthomnix@arthomnix.dev>
Date: Sat, 4 Apr 2026 19:11:34 +0100
Subject: [PATCH] further improve lunar orbit accuracy

---
 OemLoader/SystemPatch.xml | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/OemLoader/SystemPatch.xml b/OemLoader/SystemPatch.xml
index 0914591..653afc7 100644
--- a/OemLoader/SystemPatch.xml
+++ b/OemLoader/SystemPatch.xml
@@ -8,15 +8,24 @@ and a version of the "Earth and Moon" system using our new Luna. -->
         <With Path="PlanetaryBody[@Id='Luna'][2]">
             <Copy Path="@Id" Pos="Append">_Artemis2</Copy>
             <With Path="Orbit">
-                <!-- These were calculated by taking state vectors from JPL Horizons for 2026-04-06 00:00:00,
-                then using KSA's code itself to calculate the orbital parameters from there. -->
-                <Copy Path="SemiMajorAxis/@Km">387963.5088026329</Copy>
-                <Copy Path="Inclination/@Degrees">4.846183409176521</Copy>
-                <Copy Path="Eccentricity/@Value">0.04454421197470557</Copy>
-                <Copy Path="LongitudeOfAscendingNode/@Degrees">355.91022384961406</Copy>
-                <Copy Path="ArgumentOfPeriapsis/@Degrees">84.66494941290519</Copy>
-                <Copy Path="TimeAtPeriapsis/@Seconds">298420.41735839844</Copy>
+                <Delete Path="SemiMajorAxis/@Km" />
+                <Delete Path="Inclination/@Degrees" />
+                <Delete Path="LongitudeOfAscendingNode/@Degrees" />
+                <Delete Path="ArgumentOfPeriapsis/@Degrees" />
             </With>
+            <Merge Path="Orbit">
+                <!-- Based on JPL Horizons state vectors at 2026-04-06 23:00:00
+                (approx Artemis II lunar periapsis time), orbital parameters calculated
+                from state vectors using KSA code -->
+                <Orbit DefinitionFrame="Equatorial">
+                    <SemiMajorAxis M="386527231.6716702" />
+                    <Inclination Radians="0.4935872303877871" />
+                    <Eccentricity Value="0.04777738122899735" />
+                    <LongitudeOfAscendingNode Radians="6.211512996532614" />
+                    <ArgumentOfPeriapsis Radians="1.4139735506464641" />
+                    <TimeAtPeriapsis Seconds="9903893.82626691" />
+                </Orbit>
+            </Merge>
         </With>
     </With>
     
-- 
2.51.2