Index: trunk/Mars/msimreflector/MFresnelLens.cc
===================================================================
--- trunk/Mars/msimreflector/MFresnelLens.cc	(revision 19934)
+++ trunk/Mars/msimreflector/MFresnelLens.cc	(revision 19935)
@@ -474,8 +474,10 @@
 //
 // Currently calles SlopeAngleParabolic(r, F, 1, n, d)
+// Refractive Index air: https://refractiveindex.info/?shelf=other&book=air&page=Ciddor
 //
 double MFresnelLens::SlopeAngle(double r, double F, double n, double d)
 {
-    return SlopeAngleParabolic(r, F, 1.0003, n, d);
+    //return SlopeAngleAspherical(r);
+    return SlopeAngleParabolic(r, F, 1.000278, n, d);
 }