Index: trunk/Ohana/src/relphot/include/relphot.h
===================================================================
--- trunk/Ohana/src/relphot/include/relphot.h	(revision 41403)
+++ trunk/Ohana/src/relphot/include/relphot.h	(revision 41404)
@@ -486,5 +486,5 @@
 void          initMosaicGrid      PROTO((Image *image, off_t Nimage));
 void          initMosaics         PROTO((Image *subset, off_t Nsubset, Image *image, char *inSubset, off_t Nimage));
-void          initTGroups         PROTO((Image *subset, off_t *LineNumber, off_t Nsubset));
+void          initTGroups         PROTO((Image *subset, off_t Nsubset));
 void          freeTGroups         PROTO((void));
 void          initTGroupBins      PROTO((Catalog *catalog, int Ncatalog));
Index: trunk/Ohana/src/relphot/src/TGroupOps.c
===================================================================
--- trunk/Ohana/src/relphot/src/TGroupOps.c	(revision 41403)
+++ trunk/Ohana/src/relphot/src/TGroupOps.c	(revision 41404)
@@ -96,5 +96,5 @@
 
 // assign the images to the tgroups
-void initTGroups (Image *subset, off_t *LineNumber, off_t Nsubset) {
+void initTGroups (Image *subset, off_t Nsubset) {
 
   if (!TGROUP_ZEROPT) return;
@@ -133,6 +133,9 @@
     ImageToTGroup[i] = j;
 
+    // note the array 'subset' is registered in ImageOps.c:images by initImages
+    // and can be retrieve with getimages
+
     // add image to tgroup image list
-    tgroup[j].image[tgroup[j].Nimage] = i; // should this be 'i' or LineNumber[i] ??
+    tgroup[j].image[tgroup[j].Nimage] = i; // reference to entry in 'subset'
     tgroup[j].Nimage ++;
     if (tgroup[j].Nimage == tgroup[j].NIMAGE) {
@@ -190,5 +193,5 @@
     ALLOCATE_PTR (McalAPER, double, tgroup[i].Nimage);
     for (int j = 0; j < tgroup[i].Nimage; j++) {
-      int Nsub = LineNumber[tgroup[i].image[j]];
+      int Nsub = tgroup[i].image[j];
       McalPSF[j] = images[Nsub].McalPSF;
       McalAPER[j] = images[Nsub].McalAPER;
Index: trunk/Ohana/src/relphot/src/load_images.c
===================================================================
--- trunk/Ohana/src/relphot/src/load_images.c	(revision 41403)
+++ trunk/Ohana/src/relphot/src/load_images.c	(revision 41404)
@@ -110,5 +110,6 @@
   MARKTIME("init images: %f sec\n", dtime);
 
-  initTGroups (subset, LineNumber, Nsubset);
+  // assign chip images to tgroups
+  initTGroups (subset, Nsubset);
 
   return TRUE;