Index: trunk/psModules/src/objects/pmSourcePhotometry.c
===================================================================
--- trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 29546)
+++ trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 29935)
@@ -107,5 +107,5 @@
     // XXX handle negative flux, low-significance
     if (model->dparams->data.F32[PM_PAR_I0] > 0) {
-        SN = model->params->data.F32[PM_PAR_I0] / model->dparams->data.F32[PM_PAR_I0];
+        SN = fabs(model->params->data.F32[PM_PAR_I0] / model->dparams->data.F32[PM_PAR_I0]);
         source->errMag = 1.0 / SN;
     } else {
@@ -331,5 +331,5 @@
     }
     if (apFluxOut) *apFluxOut = apFlux;
-    if (apFluxErr) *apFluxErr = sqrt(apFluxVar);
+    if (apFluxErr) *apFluxErr = sqrt(fabs(apFluxVar));
 
     if (apFlux <= 0) {