Index: trunk/ippScripts/scripts/magic_tree.pl
===================================================================
--- trunk/ippScripts/scripts/magic_tree.pl	(revision 26183)
+++ trunk/ippScripts/scripts/magic_tree.pl	(revision 26186)
@@ -158,6 +158,6 @@
 
     # Relative coordinates of centre of the field
-    my $x = $naxis1 - $crpix1;
-    my $y = $naxis2 - $crpix2;
+    my $x = $naxis1/2 - $crpix1;
+    my $y = $naxis2/2 - $crpix2;
 
     # Coordinates on tangent plane
@@ -168,9 +168,14 @@
 
     # Coordinates on rotated celestial sphere
-    my $phi = atan2($eta,$xi) + pi/2;
-    my $denominator = sqrt($xi**2 + $eta**2);
-    &my_die("denominator is zero!!", $magic_id, $PS_EXIT_PROG_ERROR) if $denominator == 0;
-
-    my $theta = atan(180 / pi / $denominator);
+    my ($phi, $theta);
+    if ($xi == 0 and $eta == 0) {
+        $phi = 0;
+        $eta = 0;
+    } else {
+        $phi = atan2($eta,$xi) + pi/2;
+        my $denominator = sqrt($xi**2 + $eta**2);
+        &my_die("denominator is zero!!", $magic_id, $PS_EXIT_PROG_ERROR) if $denominator == 0;
+        $theta = atan(180 / pi / $denominator);
+    }
 
     # Coordinates on celestial sphere