Smithsonian Astrophysical Observatory (SAO) star catalog Is a Smithsonian Astrophysical Observatory (SAO) star catalog, 4 volumes, dated 1977, worth keeping in a library or is it too outdated?  Can it be used for epoch 200?
 A: Those old star catalogues will still be valuable when they are out of time. Because stars moves too slow to be perceived during a human life. With these old records astronomers can measure stars' proper motions and calculate their distances much easier.
But if you mean those heavy dusty books, it depends. Such catalogues have complete online records (for the SAO, you can find it here).  Researchers just search the database when they need it. So seldom people check these books. In my opinion, they have historical significance, but don't worth the space on your bookshelf.
A: If you are referring to the printed copy of the catalogue then I wouldn't worry much to preserve it. Unless there is something catastrophic happens and we loose our access to any electronic form of information then you could safely discard it since as gerry points out we have an online copy at our disposal.
Other thing is the usefulness of the catalogue. Every single measurement can at some stage be useful for some type of research. In my experience some of the early measurements could be invaluable in the line of episodic event study.
