Index: branches/czw_branch/20160809/psModules/src/astrom/pmAstrometryModel.c
===================================================================
--- branches/czw_branch/20160809/psModules/src/astrom/pmAstrometryModel.c	(revision 39774)
+++ branches/czw_branch/20160809/psModules/src/astrom/pmAstrometryModel.c	(revision 39777)
@@ -687,8 +687,10 @@
     char *refChip  = psMetadataLookupStr(&status, file->fpa->concepts, "REF_CHIP"); REQUIRE (status, "missing REF_CHIP");
 
+    int rotatorParity = psMetadataLookupS32(&status, file->fpa->concepts, "ROT.PARITY"); REQUIRE (status, "missing ROT.PARITY");
+    
     // XXX we've swapped the sign and parity of POS (add to model)
     // apply true posangle = -(POS - POS_ZERO)
     psLogMsg ("psModules.astrom", 4, "Position Angle: %f, Model Position Angle Zero Point: %f\n", POS, PosZero);
-    psPlaneTransform *fromTPA = psPlaneTransformRotate (NULL, file->fpa->fromTPA, (PosZero - POS));
+    psPlaneTransform *fromTPA = psPlaneTransformRotate (NULL, file->fpa->fromTPA, rotatorParity * (PosZero - POS));
     psFree (file->fpa->fromTPA);
     file->fpa->fromTPA = fromTPA;