Sample script for filtering the MPCORB file

ci/MPCORB.excerpt.DAT

@@ -0,0 +1,4 @@
+00001    3.4   0.15 K205V 162.68631   73.73161   80.28698   10.58862  0.0775571  0.21406009   2.7676569  0 MPO492748  6751 115 1801-2019 0.60 M-v 30h Williams   0000      (1) Ceres              20190915
+00002    4.2   0.15 K205V 144.97567  310.20237  173.02474   34.83293  0.2299723  0.21334458   2.7738415  0 MPO530953  8031 109 1821-2019 0.58 M-v 28h MPCW       0000      (2) Pallas             20190812
+00003    5.2   0.15 K205V 125.43538  248.06618  169.85146   12.99105  0.2569364  0.22612869   2.6682853  0 MPO530953  7023 106 1821-2020 0.59 M-v 38h MPCW       0000      (3) Juno               20200204
+00004    3.0   0.15 K205V 204.32771  150.87484  103.80908    7.14190  0.0885158  0.27150657   2.3620141  0 MPO530953  6964 102 1821-2020 0.60 M-p 18h MPCW       0000      (4) Vesta              20200203

design/mpc_make_excerpt.py

@@ -0,0 +1,30 @@
+# mpc_make_excerpt.py
+
+"""Search the MPCORB file for minor planets, given their packed designations."""
+
+import argparse
+import re
+import sys
+import zlib
+
+from skyfield.api import load
+from skyfield.data import mpc
+
+def main(argv):
+    parser = argparse.ArgumentParser(description='Grep MPCORB.DAT.gz')
+    parser.add_argument('designations', nargs='+', help='packed designations'
+                        ' of the minor planets whose orbits you need')
+    args = parser.parse_args(argv)
+
+    designations = [re.escape(d.encode('ascii')) for d in args.designations]
+    pattern = rb'^((?:%s) .*\n)' % rb'|'.join(designations)
+    r = re.compile(pattern, re.M)
+
+    data = load.open(mpc.MPCORB_URL).read()
+    data = zlib.decompress(data, wbits = zlib.MAX_WBITS | 16)
+    lines = r.findall(data)
+
+    sys.stdout.buffer.write(b''.join(lines))
+
+if __name__ == '__main__':
+    main(sys.argv[1:])