Index: /trunk/ppMops/src/ppMops.c
===================================================================
--- /trunk/ppMops/src/ppMops.c	(revision 24704)
+++ /trunk/ppMops/src/ppMops.c	(revision 24705)
@@ -83,6 +83,9 @@
         // XXX Not at all sure I've got the angles around the right way here...
         double cosAngle = cos(angle), sinAngle = sin(angle);
-        double raErr = scale * sqrt(PS_SQR(cosAngle) * PS_SQR(xErr) + PS_SQR(sinAngle) * PS_SQR(yErr));
-        double decErr = scale * sqrt(PS_SQR(sinAngle) * PS_SQR(xErr) + PS_SQR(cosAngle) * PS_SQR(yErr));
+        double cosAngle2 = PS_SQR(cosAngle), sinAngle2 = PS_SQR(sinAngle);
+        double xErr2 = PS_SQR(xErr), yErr2 = PS_SQR(yErr);
+        double errScale = scale / 3600.0;
+        double raErr = errScale * sqrt(cosAngle2 * xErr2 + sinAngle2 * yErr2);
+        double decErr = errScale * sqrt(sinAngle2 * xErr2 + cosAngle2 * yErr2);
 
         psMetadataAddF64(outRow, PS_LIST_TAIL, "RA_DEG", 0, "Right ascension (degrees)", ra);