Index: trunk/psModules/src/astrom/pmAstrometryDistortion.c
===================================================================
--- trunk/psModules/src/astrom/pmAstrometryDistortion.c	(revision 41495)
+++ trunk/psModules/src/astrom/pmAstrometryDistortion.c	(revision 41496)
@@ -234,4 +234,7 @@
     // fit the local gradients in each direction
     if (!psVectorClipFitPolynomial2D (localX, stats, mask, 0xff, dPdL, NULL, L, M)) {
+	// this failure has raised an error.  the return will also raise
+	// errors, but these are finally cleared (and bad data quality is set) in
+	// psastroAnalysis.c:143
         psLogMsg ("psastro", 3, "failed to fit x-dir gradient\n");
         psFree (localX);
@@ -241,4 +244,7 @@
 
     if (!psVectorClipFitPolynomial2D (localY, stats, mask, 0xff, dPdM, NULL, L, M)) {
+	// this failure has raised an error.  the return will also raise
+	// errors, but these are finally cleared (and bad data quality is set) in
+	// psastroAnalysis.c:143
         psLogMsg ("psastro", 3, "failed to fit y-dir gradient\n");
         psFree (localX);