Index: /trunk/Mars/NEWS
===================================================================
--- /trunk/Mars/NEWS	(revision 9860)
+++ /trunk/Mars/NEWS	(revision 9861)
@@ -66,11 +66,17 @@
       This is the time spread (rms) around the mean of the arrival times.
       It is calulated as 
-         <math>\sqrt{\sum{t_i}/n}</math>
+         <math>\sqrt{\sum{(t_i-<t>)^2}/n}</math>
    ** MHillasExt.fTimeSpreadWeighted: 
       This is the weighted time spread (rms) around the weighted mean of the arrival times.
       It is calulated as 
-         <math>\frac{1}{\sum{n_i}}\sqrt{\sum{n_i^2(t_i-<wt>)^2}}}</math>
-            or
-         <math>\frac{1}{\sum{n_i}}\sqrt{\sum{n_i^2t_i^2}+<wt>^2\sum{n_i^2}-2<wt>\sum{t_in_i^2}}</math>
+         <math>\frac{1}{\sum{w_i}}\sqrt{\sum{w_i(t_i-<wt>)^2}}}</math>
+   ** MHillasExt.fSlopeSpread: 
+      This is the time spread (rms) around the slope of the arrival times.
+      It is calulated as 
+         <math>\sqrt{\sum{(t_i-slope*(\cos\delta*x_i+\sin\delta*y_i)-<dt>)^2}/n}</math>
+   ** MHillasExt.fSlopeSpreadWeighted: 
+      This is the weighted time spread (rms) around the slope of the arrival times.
+      It is calulated as 
+         <math>\frac{1}{\sum{w_i}}\sqrt{\sum{w_i*(t_i-slope*(\cos\delta*x_i+\sin\delta*y_i)-<dt>)^2}</math>
 
  ;trainenergy.C: