Index: trunk/FACT++/src/fscctrl.cc
===================================================================
--- trunk/FACT++/src/fscctrl.cc	(revision 17394)
+++ trunk/FACT++/src/fscctrl.cc	(revision 17395)
@@ -93,9 +93,14 @@
     double GetTempPT1000(double R) const
     {
-        const double R0 = 1000; // 1kOhm
-
-        const double a = 3.893e-3;
-
-        return (R/R0 - 1)/a;
+        // This is precise within the range 5degC and 25degC
+        // by 3e-3 degC. At 0degC and 30degC it overestimates the
+        // temperature by 0.025 degC. At -10degC it is ~0.9degC
+        // and at 40degC ~0.05degC.
+        const double x = R/1000;
+        return -193.804 + 96.0651*x + 134.673*x*x - 36.9091*x*x*x;
+
+        //const double R0 = 1000; // 1kOhm
+        //const double a = 3.893e-3;
+        //return (R/R0 - 1)/a;
     }