Section 5 of 6
Catalogues
Lists made for other reasons entirely. Where every number on this site comes from, and what the lists quietly leave out.
A list of things to ignore
An eighteenth-century comet hunter kept noting fuzzy objects that were NOT comets so he would stop being fooled by them. That list of nuisances is now the most-used observing programme there is.
The bigger list
The general catalogue that followed, an order of magnitude larger and far less tidy.
Duplicates and ghosts
Entries that are the same object twice, or nothing at all.
Numbering
Why the numbers are not in any useful order.