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diff --git a/src/libcf/geod_mag.c b/src/libcf/geod_mag.c
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+/*****************************************************************************
+ *              Johns Hopkins University
+ *              Center For Astrophysical Sciences
+ *              FUSE
+ *****************************************************************************
+ *
+ * Synopsis:    double geod_mag(double lon, double lat)
+ *
+ * Description: Computes the magnetic latitude of FUSE from the
+ *              given geocentric longitude and latitude.
+ *
+ * Arguments:   double lon,lat        (deg) Geocentric longitude and latitude
+ *
+ * Returns:     double                Geomagnetic latitude.
+ *                    
+ * History:     03/11/98  E. Murphy   Begin work.
+ *              03/11/98  E. Murphy   Initial version working
+ *              04/13/99  E. Murphy   Moved PI and RADIAN to calfuse.h
+ *              12/18/03  bjg         Change calfusettag.h to calfuse.h
+ *
+ *              Ake, T. 1998 in The Scientific Impact of the Goddard
+ *                   High Resolution Spectrograph, ed. J. C. Brandt et al.,
+ *                   ASP Conference Series, in preparation.
+ ****************************************************************************/
+ 
+#include <stdio.h>
+#include <math.h>
+#include "calfuse.h"
+ 
+double geod_mag(double lon, double lat)
+{
+    double lat_rad, c1;
+
+    lat_rad=lat*RADIAN;
+
+    c1=sin(lat_rad)*cos(11.4*RADIAN)-
+        cos(lat_rad)*cos((lon+69.8)*RADIAN)*sin(11.4*RADIAN);
+
+    return asin(c1)/RADIAN;
+}