Index: trunk/psphot/src/psphotStackPSF.c
===================================================================
--- trunk/psphot/src/psphotStackPSF.c	(revision 30624)
+++ trunk/psphot/src/psphotStackPSF.c	(revision 31154)
@@ -56,8 +56,34 @@
 	}
 
-	float Sxx = sqrt(2.0)*targetFWHM / 2.35;
+	// measured scale factors (fwhm = Sxx * 2.35 * scaleFactor / sqrt(2.0))
+	// GAUSS  : 1.000
+	// PGAUSS : 1.006
+	// QGAUSS : 1.151
+	// RGAUSS : 0.883
+	// PS1_V1 : 1.134
+	
+	float scaleFactor = NAN;
+	if (!strcmp(psfModel, "PS_MODEL_GAUSS")) {
+	    scaleFactor = 1.000;
+	}
+	if (!strcmp(psfModel, "PS_MODEL_PGAUSS")) {
+	    scaleFactor = 1.0006;
+	}
+	if (!strcmp(psfModel, "PS_MODEL_QGAUSS")) {
+	    scaleFactor = 1.151;
+	}
+	if (!strcmp(psfModel, "PS_MODEL_RGAUSS")) {
+	    scaleFactor = 0.883;
+	}
+	if (!strcmp(psfModel, "PS_MODEL_PS1_V1")) {
+	    scaleFactor = 1.134;
+	}
+	psAssert (isfinite(scaleFactor), "invalid model for PSF"); 
+
+	float Sxx = sqrt(2.0)*targetFWHM / 2.35 / scaleFactor;
 
 	// XXX probably should make the model type (and par 7) optional from recipe
-	psf = pmPSFBuildSimple(psfModel, Sxx, Sxx, 0.0, 1.0);
+	// psf = pmPSFBuildSimple(psfModel, Sxx, Sxx, 0.0, 1.0);
+	psf = pmPSFBuildSimple(psfModel, Sxx, Sxx, 0.0, 0.2);
 	if (!psf) {
 	    psError(PSPHOT_ERR_PSF, false, "Unable to build dummy PSF.");