Index: branches/eam_branches/relphot.20210521/src/GridOps.c
===================================================================
--- branches/eam_branches/relphot.20210521/src/GridOps.c	(revision 41608)
+++ branches/eam_branches/relphot.20210521/src/GridOps.c	(revision 41610)
@@ -16,16 +16,4 @@
  */
 
-typedef struct {
-  unsigned short photcode;
-  float **Mgrid; // grid of average corrections
-  float **dMgrid; // grid of stdev of corrections
-    int **nMgrid; // grid of number of stars for corrections
-  int Nx; // bin = int(Xchip * (Nx / NxChip))
-  int Ny; // bin = int(Ychip * (Ny / NyChip))
-  float dX; // bin = int(Xchip * dX), dX = Nx / NxChip
-  float dY; // bin = int(Ychip * dY), dY = Ny / NyChip
-  // NxChip, NyChip = 4900,4900 for now
-} GridCorrectionType;
-
 static GridCorrectionType **GridCorr = NULL;
 static int                 NGridCorr = 0;
@@ -95,4 +83,21 @@
 
   return;
+}
+
+GridCorrectionType *getGridCorr (int *Nlast) {
+
+  if (GridCorr == NULL) return NULL;
+
+  if (*Nlast >= NGridCorr) return NULL;
+
+  if (*Nlast < 0) *Nlast = -1;
+
+  GridCorrectionType *result = NULL;
+  for (int i = *Nlast + 1; i < NGridCorr; i++) {
+    if (GridCorr[i] == NULL) continue;
+    result = GridCorr[i];
+    *Nlast = i;
+  }
+  return result;
 }