Fix MA2

Author: bkeepers

packages/tide-predictor/src/constituents/MA2.ts

@@ -3,7 +3,7 @@ import nc from "../node-corrections/index.js";
 
 /**
  * Lunar variational semi-diurnal constituent (μ2, mu2).
- * Doodson Number: 237.555
+ * Doodson Number: 545.555
  * Derived from Moon's orbital parameter variations; speed 27.968°/h with period ~12.87 hours.
  * Uses M2 nodal factors with complex variable modulation.
  *
@@ -12,4 +12,4 @@ import nc from "../node-corrections/index.js";
  *
  * @see https://iho.int/en/standards-and-specifications/standards/s-14 IHO Tidal Constituent Bank
  */
-export default defineConstituent("MA2", [2, -2, 2, 0, 0, 0, 0], nc.uM2, nc.fM2);
+export default defineConstituent("MA2", [2, 0, -1, 0, 0, 0, 0], nc.uM2, nc.fM2);

packages/tide-predictor/test/constituents/index.test.ts

@@ -51,10 +51,10 @@ describe("Base constituent definitions", () => {
   });
 
   it("has correct properties for MA2 (lunar variational semi-diurnal, mu2)", () => {
-    // MA2: [2, 0, -2, 1, 0, 0, 0]
-    // Speed: 2(T+h-s) - 2h + p ≈ 27.968208°/h
+    // MA2: [2, 0, -1, 0, 0, 0, 0]
+    // Speed: 2(T+h-s) - 2h + p ≈ 28.943°/h
     expect(constituents.MA2).toBeDefined();
-    expect(constituents.MA2.speed(testAstro)).toBeCloseTo(27.968208, 2);
+    expect(constituents.MA2.speed(testAstro)).toBeCloseTo(28.943, 3);
     expect(constituents.MA2.u(testAstro)).toBeCloseTo(constituents.M2.u(testAstro), 2);
     expect(constituents.MA2.f(testAstro)).toBeCloseTo(constituents.M2.f(testAstro), 3);
   });