Version 3.0.1.

CHANGELOG.md

@@ -1,5 +1,12 @@
 ## Changelog
 
+### 3.0.1 (2019-03-14)
+
+- Unnecessary calculations in `sgp4` function are reduced (#47).
+- `vkmpersec` calculation is moved to constants (#50). 
+- `degreesToRadians` function is used in docs instead of `deg2rad` constant (#53).
+- Typos' fixes (#54).
+
 ### 3.0.0 (2018-11-26)
 
 - Node.js 4 support is dropped (breaking change).

README.md

@@ -156,8 +156,8 @@ var positionEci = positionAndVelocity.position,
 
 // Set the Observer at 122.03 West by 36.96 North, in RADIANS
 var observerGd = {
-    longitude: -122.0308 * deg2rad,
-    latitude: 36.9613422 * deg2rad,
+    longitude: satellite.degreesToRadians(-122.0308),
+    latitude: satellite.degreesToRadians(36.9613422),
     height: 0.370
 };
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "satellite.js",
-  "version": "3.0.0",
+  "version": "3.0.1",
   "description": "SGP4/SDP4 calculation library",
   "main": "lib/index.js",
   "jsnext:main": "dist/satellite.es.js",

src/constants.js

@@ -6,6 +6,7 @@ export const minutesPerDay = 1440.0;
 export const mu = 398600.5; // in km3 / s2
 export const earthRadius = 6378.137; // in km
 export const xke = 60.0 / Math.sqrt((earthRadius * earthRadius * earthRadius) / mu);
+export const vkmpersec = (earthRadius * xke) / 60.0;
 export const tumin = 1.0 / xke;
 export const j2 = 0.00108262998905;
 export const j3 = -0.00000253215306;

src/propagation/sgp4.js

@@ -3,6 +3,7 @@ import {
   twoPi,
   earthRadius,
   xke,
+  vkmpersec,
   j2,
   j3oj2,
   x2o3,
@@ -135,8 +136,6 @@ export default function sgp4(satrec, tsince) {
 
   const temp4 = 1.5e-12;
 
-  const vkmpersec = (earthRadius * xke) / 60.0;
-
   // --------------------- clear sgp4 error flag -----------------
   satrec.t = tsince;
   satrec.error = 0;
@@ -277,7 +276,7 @@ export default function sgp4(satrec, tsince) {
       nodep,
       argpp,
       mp,
-      opsmode: satrec.operationmod,
+      opsmode: satrec.operationmode,
     };
 
     const dpperResult = dpper(satrec, dpperParameters);
@@ -383,6 +382,17 @@ export default function sgp4(satrec, tsince) {
 
   const mrt = (rl * (1.0 - (1.5 * temp2 * betal * satrec.con41)))
     + (0.5 * temp1 * satrec.x1mth2 * cos2u);
+
+  // sgp4fix for decaying satellites
+  if (mrt < 1.0) {
+    // printf("// decay condition %11.6f \n",mrt);
+    satrec.error = 6;
+    return {
+      position: false,
+      velocity: false,
+    };
+  }
+
   su -= 0.25 * temp2 * satrec.x7thm1 * sin2u;
   const xnode = nodep + (1.5 * temp2 * cosip * sin2u);
   const xinc = xincp + (1.5 * temp2 * cosip * sinip * cos2u);
@@ -417,16 +427,6 @@ export default function sgp4(satrec, tsince) {
     z: ((mvt * uz) + (rvdot * vz)) * vkmpersec,
   };
 
-  // sgp4fix for decaying satellites
-  if (mrt < 1.0) {
-    // printf("// decay condition %11.6f \n",mrt);
-    satrec.error = 6;
-    return {
-      position: false,
-      velocity: false,
-    };
-  }
-
   return {
     position: r,
     velocity: v,

src/propagation/sgp4init.js

@@ -275,7 +275,7 @@ export default function sgp4init(satrec, options) {
 
   if (omeosq >= 0.0 || satrec.no >= 0.0) {
     satrec.isimp = 0;
-    if ((rp < 220.0 / earthRadius) + 1.0) {
+    if (rp < (220.0 / earthRadius + 1.0)) {
       satrec.isimp = 1;
     }
     sfour = ss;

test/index.spec.js

@@ -9,6 +9,7 @@ import {
   mu,
   earthRadius,
   xke,
+  vkmpersec,
   tumin,
   j2,
   j3,
@@ -74,6 +75,7 @@ describe('Library export', () => {
       constantsEs.mu.should.equal(mu);
       constantsEs.earthRadius.should.equal(earthRadius);
       constantsEs.xke.should.equal(xke);
+      constantsEs.vkmpersec.should.equal(vkmpersec);
       constantsEs.tumin.should.equal(tumin);
       constantsEs.j2.should.equal(j2);
       constantsEs.j3.should.equal(j3);
@@ -116,6 +118,7 @@ describe('Library export', () => {
       constants.mu.should.equal(mu);
       constants.earthRadius.should.equal(earthRadius);
       constants.xke.should.equal(xke);
+      constants.vkmpersec.should.equal(vkmpersec);
       constants.tumin.should.equal(tumin);
       constants.j2.should.equal(j2);
       constants.j3.should.equal(j3);