diff --git a/Makefile b/Makefile
index c0a65b7..7c79088 100644
--- a/Makefile
+++ b/Makefile
@@ -6,7 +6,7 @@ SOURCES=Coord.cpp \
 	Globals.cpp \
 	Julian.cpp \
 	Observer.cpp \
-	SGDP4.cpp \
+	SGP4.cpp \
         Timespan.cpp \
 	Tle.cpp \
 	Vector.cpp  \
diff --git a/Rewrite.vcxproj b/Rewrite.vcxproj
index 665fcfe..2babb6f 100644
--- a/Rewrite.vcxproj
+++ b/Rewrite.vcxproj
@@ -81,7 +81,7 @@
     <ClCompile Include="main.cpp" />
     <ClCompile Include="Observer.cpp" />
     <ClCompile Include="SatelliteOrbit.cpp" />
-    <ClCompile Include="SGDP4.cpp" />
+    <ClCompile Include="SGP4.cpp" />
     <ClCompile Include="Timespan.cpp" />
     <ClCompile Include="Tle.cpp" />
     <ClCompile Include="Vector.cpp" />
@@ -94,7 +94,7 @@
     <ClInclude Include="Observer.h" />
     <ClInclude Include="SatelliteException.h" />
     <ClInclude Include="SatelliteOrbit.h" />
-    <ClInclude Include="SGDP4.h" />
+    <ClInclude Include="SGP4.h" />
     <ClInclude Include="Timespan.h" />
     <ClInclude Include="Tle.h" />
     <ClInclude Include="Vector.h" />
diff --git a/Rewrite.vcxproj.filters b/Rewrite.vcxproj.filters
index 9ef4fec..423268e 100644
--- a/Rewrite.vcxproj.filters
+++ b/Rewrite.vcxproj.filters
@@ -33,9 +33,6 @@
     <ClCompile Include="Tle.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="SGDP4.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
     <ClCompile Include="Observer.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -48,6 +45,9 @@
     <ClCompile Include="SatelliteOrbit.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="SGP4.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <ClInclude Include="Coord.h">
@@ -65,9 +65,6 @@
     <ClInclude Include="Tle.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="SGDP4.h">
-      <Filter>Header Files</Filter>
-    </ClInclude>
     <ClInclude Include="SatelliteException.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -83,5 +80,8 @@
     <ClInclude Include="SatelliteOrbit.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="SGP4.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/SGDP4.cpp b/SGP4.cpp
similarity index 94%
rename from SGDP4.cpp
rename to SGP4.cpp
index a2e9833..36f9530 100644
--- a/SGDP4.cpp
+++ b/SGP4.cpp
@@ -1,4 +1,4 @@
-#include "SGDP4.h"
+#include "SGP4.h"
 
 #include "Vector.h"
 #include "SatelliteException.h"
@@ -42,14 +42,14 @@
 #define TWOTHIRD (2.0 / 3.0)
 #define THDT     (4.37526908801129966e-3)
 
-SGDP4::SGDP4(void) {
+SGP4::SGP4(void) {
     first_run_ = true;
 }
 
-SGDP4::~SGDP4(void) {
+SGP4::~SGP4(void) {
 }
 
-void SGDP4::SetTle(const Tle& tle) {
+void SGP4::SetTle(const Tle& tle) {
 
     /*
      * reset all constants etc
@@ -113,7 +113,7 @@ void SGDP4::SetTle(const Tle& tle) {
     Initialize(theta2, betao2, betao, eosq);
 }
 
-void SGDP4::Initialize(const double& theta2, const double& betao2, const double& betao, const double& eosq) {
+void SGP4::Initialize(const double& theta2, const double& betao2, const double& betao, const double& eosq) {
 
     if (Period() >= 225.0) {
         i_use_deep_space_ = true;
@@ -242,7 +242,7 @@ void SGDP4::Initialize(const double& theta2, const double& betao2, const double&
     first_run_ = false;
 }
 
-void SGDP4::FindPosition(Eci& eci, double tsince) const {
+void SGP4::FindPosition(Eci& eci, double tsince) const {
 
     if (i_use_deep_space_)
         FindPositionSDP4(eci, tsince);
@@ -250,14 +250,14 @@ void SGDP4::FindPosition(Eci& eci, double tsince) const {
         FindPositionSGP4(eci, tsince);
 }
 
-void SGDP4::FindPosition(Eci& eci, const Julian& date) const {
+void SGP4::FindPosition(Eci& eci, const Julian& date) const {
 
     const double tsince = date.SpanMin(Epoch());
 
     FindPosition(eci, tsince);
 }
 
-void SGDP4::FindPositionSDP4(Eci& eci, double tsince) const {
+void SGP4::FindPositionSDP4(Eci& eci, double tsince) const {
 
     /*
      * the final values
@@ -368,7 +368,7 @@ void SGDP4::FindPositionSDP4(Eci& eci, double tsince) const {
 
 }
 
-void SGDP4::FindPositionSGP4(Eci& eci, double tsince) const {
+void SGP4::FindPositionSGP4(Eci& eci, double tsince) const {
 
     /*
      * the final values
@@ -445,7 +445,7 @@ void SGDP4::FindPositionSGP4(Eci& eci, double tsince) const {
 
 }
 
-void SGDP4::CalculateFinalPositionVelocity(Eci& eci, const double& tsince, const double& e,
+void SGP4::CalculateFinalPositionVelocity(Eci& eci, const double& tsince, const double& e,
         const double& a, const double& omega, const double& xl, const double& xnode,
         const double& xincl, const double& xlcof, const double& aycof,
         const double& x3thm1, const double& x1mth2, const double& x7thm1,
@@ -605,7 +605,7 @@ void SGDP4::CalculateFinalPositionVelocity(Eci& eci, const double& tsince, const
 /*
  * deep space initialization
  */
-void SGDP4::DeepSpaceInitialize(const double& eosq, const double& sinio, const double& cosio, const double& betao,
+void SGP4::DeepSpaceInitialize(const double& eosq, const double& sinio, const double& cosio, const double& betao,
         const double& theta2, const double& betao2,
         const double& xmdot, const double& omgdot, const double& xnodot) {
 
@@ -937,7 +937,7 @@ void SGDP4::DeepSpaceInitialize(const double& eosq, const double& sinio, const d
     }
 }
 
-void SGDP4::DeepSpaceCalculateLunarSolarTerms(const double t, double& pe, double& pinc,
+void SGP4::DeepSpaceCalculateLunarSolarTerms(const double t, double& pe, double& pinc,
         double& pl, double& pgh, double& ph) const {
 
     static const double ZES = 0.01675;
@@ -990,7 +990,7 @@ void SGDP4::DeepSpaceCalculateLunarSolarTerms(const double t, double& pe, double
 /*
  * calculate lunar / solar periodics and apply
  */
-void SGDP4::DeepSpacePeriodics(const double& t, double& em,
+void SGP4::DeepSpacePeriodics(const double& t, double& em,
         double& xinc, double& omgasm, double& xnodes, double& xll) const {
 
     /*
@@ -1085,7 +1085,7 @@ void SGDP4::DeepSpacePeriodics(const double& t, double& em,
 /*
  * deep space secular effects
  */
-void SGDP4::DeepSpaceSecular(const double& t, double& xll, double& omgasm,
+void SGP4::DeepSpaceSecular(const double& t, double& xll, double& omgasm,
         double& xnodes, double& em, double& xinc, double& xn) const {
 
     static const double STEP = 720.0;
@@ -1170,7 +1170,7 @@ void SGDP4::DeepSpaceSecular(const double& t, double& xll, double& omgasm,
 /*
  * calculate dot terms
  */
-void SGDP4::DeepSpaceCalcDotTerms(double& xndot, double& xnddt, double& xldot) const {
+void SGP4::DeepSpaceCalcDotTerms(double& xndot, double& xnddt, double& xldot) const {
 
     static const double G22 = 5.7686396;
     static const double G32 = 0.95240898;
@@ -1225,7 +1225,7 @@ void SGDP4::DeepSpaceCalcDotTerms(double& xndot, double& xnddt, double& xldot) c
 /*
  * deep space integrator for time period of delt
  */
-void SGDP4::DeepSpaceIntegrator(const double delt, const double step2,
+void SGP4::DeepSpaceIntegrator(const double delt, const double step2,
         const double xndot, const double xnddt, const double xldot) const {
 
     /*
@@ -1240,7 +1240,7 @@ void SGDP4::DeepSpaceIntegrator(const double delt, const double step2,
     d_atime_ += delt;
 }
 
-void SGDP4::ResetGlobalVariables() {
+void SGP4::ResetGlobalVariables() {
 
     /*
      * common variables
diff --git a/SGDP4.h b/SGP4.h
similarity index 94%
rename from SGDP4.h
rename to SGP4.h
index a9d17cf..f14d89b 100644
--- a/SGDP4.h
+++ b/SGP4.h
@@ -4,10 +4,10 @@
 #include "Tle.h"
 #include "Eci.h"
 
-class SGDP4 {
+class SGP4 {
 public:
-    SGDP4(void);
-    virtual ~SGDP4(void);
+    SGP4(void);
+    virtual ~SGP4(void);
 
     void SetTle(const Tle& tle);
     void FindPosition(Eci& eci, double tsince) const;
diff --git a/SatelliteOrbit.h b/SatelliteOrbit.h
index 56b0502..d56d9f2 100644
--- a/SatelliteOrbit.h
+++ b/SatelliteOrbit.h
@@ -2,7 +2,7 @@
 #define SATELLITEORBIT_H_
 
 #include "Tle.h"
-#include "SGDP4.h"
+#include "SGP4.h"
 
 class SatelliteOrbit {
 public:
@@ -16,7 +16,7 @@ public:
     unsigned int GetOrbitNumber(const Julian& jul) const;
 
 private:
-    SGDP4 sgdp4_;
+    SGP4 sgdp4_;
 };
 
 #endif
diff --git a/main.cpp b/main.cpp
index 0d145b2..eb5d825 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,6 +1,6 @@
 #include "Julian.h"
 #include "Tle.h"
-#include "SGDP4.h"
+#include "SGP4.h"
 #include "Globals.h"
 #include "Observer.h"
 #include "Coord.h"
@@ -22,7 +22,7 @@ void FindSatellite(const Julian& time_start, const Julian& time_end) {
 
 }
 
-void GeneratePassList(const CoordGeodetic& geo, const SGDP4& model, const Julian& date) {
+void GeneratePassList(const CoordGeodetic& geo, const SGP4& model, const Julian& date) {
     Observer obs(geo);
     Eci eci;
     model.FindPosition(eci, date);
@@ -52,7 +52,7 @@ int main() {
 
     CoordGeodetic geo(Globals::Deg2Rad(51.360242), Globals::Deg2Rad(0.101473), 0.07);
 
-    SGDP4 sgp4_model;
+    SGP4 sgp4_model;
     sgp4_model.SetTle(tle);
     Julian date;