But I do advocate [[WP:V|A third party source]] as a minimum inclusion criterion (Perhaps this is why I've been called "an inclusionist troll"), and only galaxies which've been catalogued in some publication should have articles - maybe 2 million tops. Which some such articles might not be of interested again for a while, they're certainly verifiable and encyclopaedic, and not doing any harm.
If they haven't been mentioned in anything more than a catalogue, it's impossible to write more than a sentence about them (name, date of discovery and location is about it). I thought substubs were frowned opon.