B.4 Boundaries data file

It doesn't make much sense to use an own boundaries file, unless you want to use a different equinox, but anyway. This is a text file usually called boundaries.dat. It has no header.

The file is a sequence of elementary line segments. Every segment is a whitespace separated sequence of entries. The entries for each segment are:

1. Number of points n_1 in the segment.
2. Repeated n_1 times:
   1. rectascension of point in hours,
   2. declination of point in degrees.
3. Number of constellations n_2 touching this border line (is always 2, however it hasn't always been due to flawed raw data).
4. Repeated n_2 times: All uppercase astronomical abbreviation of the adjacent constellation. It may distinguish between SER1 and SER2 for Serpens Caput and Serpens Cauda.

Example

     3 20.63865 2.43608 20.63929 1.43613 20.63992 0.43617 2 AQL AQR
     10 20.63992 0.43617 20.64055 -0.56377 20.64118 -1.56373
       20.64181 -2.56368 20.64245 -3.56364 20.64308 -4.56359 20.64372 -5.56355
       20.64435 -6.56350 20.64500 -7.56346 20.64564 -8.56341 2 AQL AQR
     9 17.71838 -67.57110 17.65152 -67.58319 17.58465 -67.59526
       17.51772 -67.60731 17.45076 -67.61933 17.38378 -67.63130 17.31676 -67.64324
       17.24970 -67.65515 17.21616 -67.66108 2 ARA APS

PP3's boundary data origin

It's the Catalogue of Constellation Boundary Data by Davenhall and Leggett. I had to fix some bugs though, because the Ophiuchus/Serpens region was flawed. Additionally, the original data has peculiarities because it tries to be useful for bounded maps, e.g. in Mercator projection. I removed the resulting spurious lines.