new: pulse center of gravity

src/scgenerator/spectra.py

@@ -122,6 +122,11 @@ class Spectrum(np.ndarray):
             return self.l[np.argmax(self.wl_int, axis=-1)]
         return np.array([s.wl_max for s in self])
 
+    @property
+    def center_of_gravity(self):
+        intensity = self.time_int
+        return np.sum(intensity * self.t) / np.sum(intensity)
+
     def mask_wl(self, pos: float, width: float) -> Spectrum:
         """
         Filters the spectrum with a bandpass centered at `pos` of FWHM `width`.