A2.0 from USNO-cat on HD: no file for tdf, no tdf,
no user dataset, it seems a program part from GUIDE9
A2.0=usno_a2.txt from VIZIER in vizier.tdf, works well
B1 =b10.dat from VIZIER in gsc22.tdf, works well
(both tdf in guide9-dvd\text)
The B1-cat I don't have on my harddrive but seems easy to
write a tdf that works.
I think it's a good idea to manage the catalogs themselves
but I'm not a c-programmer and so I can't follow your example.