Index: /trunk/psphot/src/psphotRadiusChecks.c
===================================================================
--- /trunk/psphot/src/psphotRadiusChecks.c	(revision 10136)
+++ /trunk/psphot/src/psphotRadiusChecks.c	(revision 10137)
@@ -4,12 +4,16 @@
 static float PSF_FIT_NSIGMA;
 static float PSF_FIT_PADDING;
+static float PSF_FIT_RADIUS = 0;	// radius to use in fitting (ignored if <= 0,
+					// and a per-object radius is calculated)
 static pmModelRadius modelRadiusPSF;
 
-bool psphotInitRadiusPSF (psMetadata *recipe, pmModelType type) {
+bool psphotInitRadiusPSF(const psMetadata *recipe,
+			 const pmModelType type)
+{
+    bool status = true;
 
-    bool status;
-
-    PSF_FIT_NSIGMA   = psMetadataLookupF32 (&status, recipe, "PSF_FIT_NSIGMA");
-    PSF_FIT_PADDING  = psMetadataLookupF32 (&status, recipe, "PSF_FIT_PADDING");
+    PSF_FIT_NSIGMA  = psMetadataLookupF32(&status, recipe, "PSF_FIT_NSIGMA");
+    PSF_FIT_PADDING = psMetadataLookupF32(&status, recipe, "PSF_FIT_PADDING");
+    PSF_FIT_RADIUS =  psMetadataLookupF32(&status, recipe, "PSF_FIT_RADIUS");
 
     // this function specifies the radius at this the model hits the given flux
@@ -19,11 +23,16 @@
 
 // call this function whenever you (re)-define the PSF model
-bool psphotCheckRadiusPSF (pmReadout *readout, pmSource *source, pmModel *model) {
-
+bool psphotCheckRadiusPSF (pmReadout *readout, pmSource *source, pmModel *model)
+{
     pmMoments *moments = source->moments;
     if (moments == NULL) return false;
 
     // set the fit radius based on the object flux limit and the model
-    model->radiusFit = (RADIUS_TYPE) (modelRadiusPSF (model->params, PSF_FIT_NSIGMA*moments->dSky) + PSF_FIT_PADDING);
+    float radiusFit = PSF_FIT_RADIUS;
+    if (radiusFit <= 0) {		// use fixed radius
+	radiusFit = modelRadiusPSF(model->params, PSF_FIT_NSIGMA*moments->dSky);
+    }
+    model->radiusFit = (RADIUS_TYPE)(RadiusFit + PSF_FIT_PADDING);
+
     if (isnan(model->radiusFit)) psAbort ("apply_psf_model", "error in radius");