Add bin/radec.py: Convert coordinate among different formats

1 files changed, 57 insertions, 0 deletions

diff --git a/bin/radec.py b/bin/radec.py
new file mode 100755
index 0000000..4cc2b71
--- /dev/null
+++ b/bin/radec.py
@@ -0,0 +1,57 @@
+#!/usr/bin/env python3
+#
+# Copyright (c) 2017 Aaron LI <aly@aaronly.me>
+# MIT License
+#
+
+"""
+Convert among various (R.A., Dec.) coordinate formats.
+"""
+
+import argparse
+
+from astropy import units as au
+from astropy.coordinates import Angle
+
+
+def parse_coord(c):
+    if len(c) == 6:
+        # h m s d m s
+        ra = Angle((float(c[0]), float(c[1]), float(c[2])), unit=au.hourangle)
+        dec = Angle((float(c[3]), float(c[4]), float(c[5])), unit=au.deg)
+    elif len(c) == 2:
+        ra = Angle(float(c[0]), unit=au.deg)
+        dec = Angle(float(c[1]), unit=au.deg)
+    else:
+        raise ValueError("invalid coordinate: {0}".format(c))
+    return (ra, dec)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Convert among multiple coordinate formats")
+    parser.add_argument("coord", nargs="+")
+    args = parser.parse_args()
+
+    ra, dec = parse_coord(args.coord)
+    info = (
+        "%-14s  %-14s\n" % ("R.A.", "Dec.") +
+        "%s--%s\n" % ("-"*14, "-"*14) +
+        "%-14.3f  %-+14.3f\n" % (ra.deg, dec.deg) +
+        "%-14s  %-14s\n" % (
+            ra.to_string(unit=au.hourangle, precision=4),
+            dec.to_string(unit=au.deg, alwayssign=True, precision=3)) +
+        "%-14s  %-14s\n" % (
+            ra.to_string(unit=au.hourangle, sep=":", precision=4),
+            dec.to_string(unit=au.deg, alwayssign=True,
+                          sep=":", precision=3)) +
+        "%-14s  %-14s\n" % (
+            ra.to_string(unit=au.hourangle, sep=" ", precision=4),
+            dec.to_string(unit=au.deg, alwayssign=True,
+                          sep=" ", precision=3))
+    )
+    print(info)
+
+
+if __name__ == "__main__":
+    main()