Index: trunk/psModules/src/objects/pmSourcePhotometry.c
===================================================================
--- trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 9924)
+++ trunk/psModules/src/objects/pmSourcePhotometry.c	(revision 9925)
@@ -3,6 +3,6 @@
  *  @author EAM, IfA; GLG, MHPCC
  *
- *  @version $Revision: 1.16 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2006-11-07 09:11:12 $
+ *  @version $Revision: 1.17 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2006-11-09 20:17:10 $
  *
  *  Copyright 2004 Maui High Performance Computing Center, University of Hawaii
@@ -132,9 +132,65 @@
         float dx = 0.5 - x + (int)x;
         float dy = 0.5 - y + (int)y;
+        x += dx;
+        y += dy;
         flux = psImageShift (NULL, source->pixels, dx, dy, 0.0, PS_INTERPOLATE_BICUBE);
+        // flux = psImageShift (NULL, source->pixels, dx, dy, 0.0, PS_INTERPOLATE_BILINEAR);
+
+        // XXX this is test code to verify the shift is doing the right thing (seems to be)
+        # if (0)
+            // measure centroid of unshifted gaussian (should be 16.0,16.0)
+        {
+            psImage *image = source->pixels;
+            float xo = 0.0;
+            float yo = 0.0;
+            float xo2 = 0.0;
+            float yo2 = 0.0;
+            float no = 0.0;
+            for (int j = 0; j < image->numRows; j++)
+            {
+                for (int i = 0; i < image->numCols; i++) {
+                    xo += i*image->data.F32[j][i];
+                    yo += j*image->data.F32[j][i];
+                    xo2 += i*i*image->data.F32[j][i];
+                    yo2 += j*j*image->data.F32[j][i];
+                    no += image->data.F32[j][i];
+                }
+            }
+            xo /= no;
+            yo /= no;
+            xo2 = sqrt (xo2/no - xo*xo);
+            yo2 = sqrt (yo2/no - yo*yo);
+            fprintf (stderr, "pre-shift centroid: %f,%f, sigma: %f,%f: flux: %f\n", xo, yo, xo2, yo2, no);
+        }
+
+        // measure centroid of unshifted gaussian (should be 16.0,16.0)
+        {
+            psImage *image = flux;
+            float xo = 0.0;
+            float yo = 0.0;
+            float xo2 = 0.0;
+            float yo2 = 0.0;
+            float no = 0.0;
+            for (int j = 0; j < image->numRows; j++)
+            {
+                for (int i = 0; i < image->numCols; i++) {
+                    xo += i*image->data.F32[j][i];
+                    yo += j*image->data.F32[j][i];
+                    xo2 += i*i*image->data.F32[j][i];
+                    yo2 += j*j*image->data.F32[j][i];
+                    no += image->data.F32[j][i];
+                }
+            }
+            xo /= no;
+            yo /= no;
+            xo2 = sqrt (xo2/no - xo*xo);
+            yo2 = sqrt (yo2/no - yo*yo);
+            fprintf (stderr, "pre-shift centroid: %f,%f, sigma: %f,%f: flux: %f\n", xo, yo, xo2, yo2, no);
+        }
+        # endif
+
     } else {
         flux = source->pixels;
     }
-
     // set aperture mask circle to model radius
     // XXX use a different radius for apertures and fits...