Index: /branches/pap/psModules/src/objects/models/pmModel_PS1_V1.c
===================================================================
--- /branches/pap/psModules/src/objects/models/pmModel_PS1_V1.c	(revision 25717)
+++ /branches/pap/psModules/src/objects/models/pmModel_PS1_V1.c	(revision 25718)
@@ -265,10 +265,16 @@
     psF32 *PAR = params->data.F32;
 
-    if (flux <= 0)
-        return (1.0);
-    if (PAR[PM_PAR_I0] <= 0)
-        return (1.0);
-    if (flux >= PAR[PM_PAR_I0])
-        return (1.0);
+    if (flux <= 0) {
+        return 1.0;
+    }
+    if (PAR[PM_PAR_I0] <= 0) {
+        return 1.0;
+    }
+    if (flux >= PAR[PM_PAR_I0]) {
+        return 1.0;
+    }
+    if (PAR[PM_PAR_7] == 0.0) {
+        return powf(PAR[PM_PAR_I0] / flux - 1.0, 1.0 / ALPHA);
+    }
 
     shape.sx  = PAR[PM_PAR_SXX] / M_SQRT2;