diff --git a/include/GResponse.hpp b/include/GResponse.hpp
index 26713e7..0e90a8b 100644
--- a/include/GResponse.hpp
+++ b/include/GResponse.hpp
@@ -4,10 +4,18 @@
  *  copyright (C) 2008-2011 by Jurgen Knodlseder                           *
  * ----------------------------------------------------------------------- *
  *                                                                         *
- *   This program is free software; you can redistribute it and/or modify  *
- *   it under the terms of the GNU General Public License as published by  *
- *   the Free Software Foundation; either version 2 of the License, or     *
- *   (at your option) any later version.                                   *
+ *  This program is free software: you can redistribute it and/or modify   *
+ *  it under the terms of the GNU General Public License as published by   *
+ *  the Free Software Foundation, either version 3 of the License, or      *
+ *  (at your option) any later version.                                    *
+ *                                                                         *
+ *  This program is distributed in the hope that it will be useful,        *
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of         *
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the          *
+ *  GNU General Public License for more details.                           *
+ *                                                                         *
+ *  You should have received a copy of the GNU General Public License      *
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.  *
  *                                                                         *
  ***************************************************************************/
 /**
diff --git a/src/obs/GResponse.cpp b/src/obs/GResponse.cpp
index bed386f..8eec4de 100644
--- a/src/obs/GResponse.cpp
+++ b/src/obs/GResponse.cpp
@@ -271,6 +271,24 @@ double GResponse::irf_diffuse(const GInstDir&            obsDir,
 
 
 /***********************************************************************//**
+ * @brief Return maximum IRF radius (in radians)
+ *
+ * @param[in] srcEng True energy of photon.
+ *
+ * This method returns the radius beyond which the IRF can be assumed to be
+ * zero. By default this method returns pi (hence no limiting IRF radius).
+ * Implementing a maximum IRF radius helps the convergence of the Npred
+ * integration routine, and brings down computation time to an affordable
+ * amount.
+ ***************************************************************************/
+double GResponse::irf_max_radius(const GEnergy& srcEng) const
+{
+    // Return pi
+    return pi;
+}
+
+
+/***********************************************************************//**
  * @brief Return data space integral of instrument response function
  *
  * @param[in] model Source model.
@@ -345,7 +363,7 @@ double GResponse::npred_extended(const GModelExtendedSource& model,
 {
     // Initialise Npred value
     double npred = 0.0;
-
+    
     // Compute rotation matrix to convert from native coordinates given by
     // (theta,phi) into celestial coordinates.
     GMatrix ry;