Index: trunk/psModules/src/objects/pmSourcePhotometry.c
===================================================================
--- trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 34498)
+++ trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 36375)
@@ -113,4 +113,12 @@
     source->apFluxErr = NAN;
 
+    pmModelStatus badModel = PM_MODEL_STATUS_NONE;
+    badModel |= PM_MODEL_STATUS_BADARGS;
+    badModel |= PM_MODEL_STATUS_OFFIMAGE;
+    badModel |= PM_MODEL_STATUS_NAN_CHISQ;
+    badModel |= PM_MODEL_SERSIC_PCM_FAIL_GUESS;
+    badModel |= PM_MODEL_SERSIC_PCM_FAIL_GRID;
+    badModel |= PM_MODEL_PCM_FAIL_GUESS;
+
     // XXXXXX review:
     // Select the 'best' model -- this is used for PSF_QF,_PERFECT & ???. isPSF is true if this
@@ -162,5 +170,5 @@
         for (int i = 0; i < source->modelFits->n; i++) {
             pmModel *model = source->modelFits->data[i];
-	    if (model->flags & PM_MODEL_STATUS_BADARGS) continue;
+	    if (model->flags & badModel) continue;
             status = pmSourcePhotometryModel (&model->mag, NULL, model);
             if (model == source->modelEXT) foundEXT = true;
@@ -902,4 +910,40 @@
 }
 
+bool pmSourceChisqModelFlux (pmSource *source, pmModel *model, psImageMaskType maskVal)
+{
+    PS_ASSERT_PTR_NON_NULL(source, false);
+    PS_ASSERT_PTR_NON_NULL(model, false);
+
+    float dC = 0.0;
+    int Npix = 0;
+
+    psVector *params = model->params;
+    psImage  *image = source->pixels;
+    psImage  *modelFlux = source->modelFlux;
+    psImage  *mask = source->maskObj;
+    psImage  *variance = source->variance;
+
+    float Io = params->data.F32[PM_PAR_I0];
+
+    for (int iy = 0; iy < image->numRows; iy++) {
+        for (int ix = 0; ix < image->numCols; ix++) {
+
+	    // skip pixels which are masked
+            if (mask->data.PS_TYPE_IMAGE_MASK_DATA[iy][ix] & maskVal) continue;
+
+            if (variance->data.F32[iy][ix] <= 0) continue;
+
+            dC += PS_SQR (image->data.F32[iy][ix] - Io*modelFlux->data.F32[iy][ix]) / variance->data.F32[iy][ix];
+            Npix ++;
+        }
+    }
+    model->nPix = Npix;
+    model->nDOF = Npix - model->nPar;
+    model->chisq = dC;
+    model->chisqNorm = dC / model->nDOF;
+
+    return (true);
+}
+
 double pmSourceModelWeight(const pmSource *Mi, int term, const pmSourceFitVarMode fitVarMode, const float covarFactor, psImageMaskType maskVal)
 {