#88: added jd2hjd script to compare VStar against an even more accurate implementation

Author: dbenn

script/jd2hjd.py

@@ -0,0 +1,30 @@
+from astropy.time import Time
+from astropy.coordinates import SkyCoord, EarthLocation
+import astropy.units as u
+
+import sys
+
+
+def jd2hjd(jd: float, ra: float, dec: float) -> float:
+    # 1. Define input time, location (, and target
+    jd_time = Time(jd, format='jd', scale='utc')
+    # Klemzig (how much difference does location make for our purposes?)
+    location = EarthLocation(lat=34.88*u.deg, lon=138.64*u.deg, height=60*u.m) 
+    target = SkyCoord(ra=ra*u.deg, dec=dec*u.deg)
+
+    # 2. Calculate light travel time to heliocenter (or barycenter)
+    ltt_hjd = jd_time.light_travel_time(target, 'heliocentric', location=location)
+
+    # 3. Apply correction
+    hjd_time = jd_time + ltt_hjd
+
+    return hjd_time
+
+
+if __name__ == "__main__":
+    if len(sys.argv) == 4:
+        jd = float(sys.argv[1])
+        ra = float(sys.argv[2])
+        dec = float(sys.argv[3])
+        hjd = jd2hjd(jd, ra, dec) 
+        print(f"{jd} => {hjd}")