ne_sw derivatives

src/pint/models/dispersion_model.py

@@ -206,10 +206,10 @@ def validate(self):
                 )
 
     def DM_derivative_unit(self, n):
-        return "pc cm^-3/yr^%d" % n if n else "pc cm^-3"
+        return f"pc cm^-3/yr^{n}" if n != 0 else "pc cm^-3"
 
     def DM_derivative_description(self, n):
-        return "%d'th time derivative of the dispersion measure" % n
+        return f"{n}'th time derivative of the dispersion measure"
 
     def get_DM_terms(self):
         """Return a list of the DM term values in the model: [DM, DM1, ..., DMn]"""

src/pint/models/solar_wind_dispersion.py

@@ -302,6 +302,17 @@ def __init__(self):
                 tcb2tdb_scale_factor=(const.c * DMconst),
             )
         )
+        self.add_param(
+            floatParameter(
+                name="NE_SW1",
+                units="cm^-3",
+                value=0.0,
+                description="Derivative of Solar Wind density at 1 AU",
+                unit_template=self.NE_SW_derivative_unit,
+                description_template=self.NE_SW_derivative_description,
+                tcb2tdb_scale_factor=(const.c * DMconst),
+            )
+        )
         self.add_param(
             floatParameter(
                 name="SWP",
@@ -329,6 +340,12 @@ def setup(self):
         self.register_dm_deriv_funcs(self.d_dm_d_swp, "SWP")
         self.register_deriv_funcs(self.d_delay_d_swp, "SWP")
 
+    def NE_SW_derivative_unit(self, n):
+        return f"cm^-3/yr^{n}" if n != 0 else "cm^-3"
+
+    def NE_SW_derivative_description(self, n):
+        return f"{n}'th time derivative of the Solar Wind density at 1 AU"
+
     def solar_wind_geometry(self, toas):
         """Return the geometry of solar wind dispersion.