Index: trunk/psphot/src/psphotChoosePSF.c
===================================================================
--- trunk/psphot/src/psphotChoosePSF.c	(revision 10076)
+++ trunk/psphot/src/psphotChoosePSF.c	(revision 10096)
@@ -26,4 +26,10 @@
     }
 
+    // supply the measured sky variance for optional constant errors (non-poissonian)
+    float SKY_STDEV = psMetadataLookupF32 (&status, recipe, "SKY_STDEV");
+    if (!status) {
+	SKY_STDEV = 1.0;
+        psWarning("SKY_STDEV is not set --- defaulting to %f\n", SKY_STDEV);
+    }
     // use poissonian errors or local-sky errors
     bool POISSON_ERRORS = psMetadataLookupBool (&status, recipe, "POISSON_ERRORS");
@@ -32,4 +38,5 @@
         psWarning("POISSON_ERRORS is not set in the recipe --- defaulting to true.\n");
     }
+    pmSourceFitModelInit (15, 0.01, PS_SQR(SKY_STDEV), POISSON_ERRORS);
 
     // how to model the PSF variations across the field
@@ -48,6 +55,4 @@
     }
 
-    pmSourceFitModelInit (15, 0.1, POISSON_ERRORS);
-
     stars = psArrayAllocEmpty (sources->n);
 
@@ -94,15 +99,4 @@
         modelName = item->data.V;
         models->data[i] = pmPSFtryModel (stars, modelName, RADIUS, POISSON_ERRORS, psfTrendMask);
-    }
-
-    // XXX test dump of psf stars and model
-    if (1) { 
-	psphotSaveImage (NULL, readout->image,  "testsub.fits");
-	pmSourcesWritePSFs (stars, "psfstars.dat");
-	try = models->data[0];
-	psf = try->psf;
-	psMetadata *psfData = pmPSFtoMetadata (NULL, psf);
-        psMetadataConfigWrite (psfData, "psfmodel.dat");
-	psFree (psfData);
     }
 
@@ -138,4 +132,30 @@
     try = models->data[bestN];
 
+    // XXX test dump of psf star data and psf-subtracted image
+    if (0) { 
+	for (int i = 0; i < try->sources->n; i++) {
+	    // masked for: bad model fit, outlier in parameters
+	    if (try->mask->data.U8[i] & PSFTRY_MASK_ALL)
+		continue;
+
+	    pmSource *source = try->sources->data[i];
+	    float x = source->modelPSF->params->data.F32[PM_PAR_XPOS];
+	    float y = source->modelPSF->params->data.F32[PM_PAR_YPOS];
+
+	    // set the mask and subtract the PSF model
+	    psImageKeepCircle (source->mask, x, y, RADIUS, "OR", PM_MASK_MARK);
+	    pmModelSub (source->pixels, source->mask, source->modelPSF, false, false);
+	    psImageKeepCircle (source->mask, x, y, RADIUS, "AND", PS_NOT_U8(PM_MASK_MARK));
+	}
+
+	psphotSaveImage (NULL, readout->image,  "psfstars.fits");
+	pmSourcesWritePSFs (try->sources, "psfstars.dat");
+	psMetadata *psfData = pmPSFtoMetadata (NULL, try->psf);
+	psMetadataConfigWrite (psfData, "psfmodel.dat");
+	psFree (psfData);
+	psLogMsg ("psphot.choosePSF", 3, "wrote out psf-subtracted image, psf data, exiting\n");
+	exit (0);
+    }
+
     // unset the PSFSTAR flag for stars not used for PSF model
     for (int i = 0; i < try->sources->n; i++) {