diff --git a/ChangeLog b/ChangeLog
index 15a96d5ab6b6f4a01c1c4f6bb2f6ceb03c90dada..b625d61a652cca3cbd7a2df2551dfb32e1ea89b8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2024-09-17  Richard Larsson <ric.larsson@gmail.com>
+
+	* Port the files from ARTS-XML-DATA-2.6-3
+
 2023-10-11  Richard Larsson <ric.larsson@gmail.com>
 
 	* ARTS-XML-DATA-2-6-1
diff --git a/planets/Earth/Optimized-Flux-Frequencies/LW-flux-optimized-f_grid.xml b/planets/Earth/Optimized-Flux-Frequencies/LW-flux-optimized-f_grid.xml
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+++ b/planets/Earth/Optimized-Flux-Frequencies/LW-flux-optimized-f_grid.xml
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diff --git a/planets/Earth/Optimized-Flux-Frequencies/LW-flux-optimized-quadrature_weights.xml b/planets/Earth/Optimized-Flux-Frequencies/LW-flux-optimized-quadrature_weights.xml
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+++ b/planets/Earth/Optimized-Flux-Frequencies/LW-flux-optimized-quadrature_weights.xml
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diff --git a/planets/Earth/Optimized-Flux-Frequencies/SW-flux-optimized-f_grid.xml b/planets/Earth/Optimized-Flux-Frequencies/SW-flux-optimized-f_grid.xml
new file mode 100644
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+++ b/planets/Earth/Optimized-Flux-Frequencies/SW-flux-optimized-f_grid.xml
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diff --git a/planets/Earth/Optimized-Flux-Frequencies/SW-flux-optimized-quadrature_weights.xml b/planets/Earth/Optimized-Flux-Frequencies/SW-flux-optimized-quadrature_weights.xml
new file mode 100644
index 0000000000000000000000000000000000000000..80826010cad776fe14e19acdb403b2806780fb8b
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+++ b/planets/Earth/Optimized-Flux-Frequencies/SW-flux-optimized-quadrature_weights.xml
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diff --git a/planets/Earth/Optimized-Flux-Frequencies/readme b/planets/Earth/Optimized-Flux-Frequencies/readme
new file mode 100644
index 0000000000000000000000000000000000000000..c5d40509fd22c46b7ec4a543448d86861257838f
--- /dev/null
+++ b/planets/Earth/Optimized-Flux-Frequencies/readme
@@ -0,0 +1,14 @@
+This folder contains optimized set of frequencies and quadrature weights
+from Paulina Czarnecki for fast long and shortwave flux calculations.
+
+Use the frequencies as f_grid for the radiative transfer simulation and 
+the weights for the spectral integration.
+
+Originally the frequencies and weights were in the units of wavenumbers but 
+they are converted to Hz.
+
+For details on the algorithm for the frequency selection and weight estimation
+see:
+P. Czarnecki, L. Polvani, R. Pincus, Sparse, empirically optimized quadrature 
+for broadband spectral integration, Journal of Advances in Modeling Earth 
+Systems 15 (10) (2023) https://doi.org/10.1029/2023MS003819