Merge pull request #411 from observerly/feature/aberration/getCorrectionToEquatorialForAberration

Author: michealroberts

src/aberration.ts

@@ -153,3 +153,34 @@ export const getCorrectionToEquatorialForDiurnalAberration = (
 }
 
 /*****************************************************************************************************************/
+
+/**
+ *
+ * getCorrectionToEquatorialForAberration()
+ *
+ * Corrects the equatorial coordinate of a target for aberration in
+ * longitude and obliquity due to the apparent motion of the Earth.
+ *
+ * @param date - The date to correct the equatorial coordinate for.
+ * @param target - The equatorial J2000 coordinate of the target.
+ * @returns The corrected equatorial coordinate of the target.
+ *
+ */
+export const getCorrectionToEquatorialForAberration = (
+  datetime: Date,
+  observer: GeographicCoordinate,
+  target: EquatorialCoordinate
+): EquatorialCoordinate => {
+  // Get the annual aberration correction:
+  const annual = getCorrectionToEquatorialForAnnualAberration(datetime, target)
+
+  // Get the diurnal aberration correction:
+  const diurnal = getCorrectionToEquatorialForDiurnalAberration(datetime, observer, target)
+
+  return {
+    ra: annual.ra + diurnal.ra,
+    dec: annual.dec + diurnal.dec
+  }
+}
+
+/*****************************************************************************************************************/

tests/aberration.spec.ts

@@ -10,7 +10,12 @@ import { describe, expect, it } from 'vitest'
 
 /*****************************************************************************************************************/
 
-import { type EquatorialCoordinate, getCorrectionToEquatorialForAnnualAberration, getCorrectionToEquatorialForDiurnalAberration } from '../src'
+import {
+  type EquatorialCoordinate,
+  getCorrectionToEquatorialForAberration,
+  getCorrectionToEquatorialForAnnualAberration,
+  getCorrectionToEquatorialForDiurnalAberration,
+} from '../src'
 
 /*****************************************************************************************************************/
 
@@ -80,4 +85,34 @@ describe('getCorrectionToEquatorialForDiurnalAberration', () => {
   })
 })
 
+/*****************************************************************************************************************/
+
+describe('getCorrectionToEquatorialForAberration', () => {
+  it('should be defined', () => {
+    expect(getCorrectionToEquatorialForAberration).toBeDefined()
+  })
+
+  it('should return the correct aberration correction for the J2000 default epoch', () => {
+    const { ra, dec } = getCorrectionToEquatorialForAberration(
+      new Date('2000-01-01T00:00:00+00:00'),
+      {
+        latitude,
+        longitude
+      },
+      betelgeuse
+    )
+    expect(ra + betelgeuse.ra).toBe(88.79875665605677)
+    expect(dec + betelgeuse.dec).toBe(7.406836962857944)
+  })
+
+  it('should return the correct aberration correction for the designated epoch', () => {
+    const { ra, dec } = getCorrectionToEquatorialForAberration(datetime, {
+      latitude,
+      longitude
+    }, betelgeuse)
+    expect(ra + betelgeuse.ra).toBe(88.78844263611573)
+    expect(dec + betelgeuse.dec).toBe(7.4061425995174766)
+  })
+})
+
 /*****************************************************************************************************************/