Good day to you all! This is my first post here but I am not a n00b to forums or science. I hope you all find this an interesting topic and we can find some answers. For the last few weeks I've been searching the net for definitions to the acronyms we use in classifying extremly deep space galaxies and quasars.

Here is what I have found so far:

A - Abell - a class of galaxy clusters or groups of galaxies (also ABCG, AC and ACO)

Arp - Halton Arp Atlas Peculiar galaxies - odd shaped glaxies.

M - Messier - A smaller collection of ~110 galactic object farthest of which is 50 million light years

NGC - New General Catalog - the best known system of tracking most galaxies within 75 million light years

PKS - Perek-Kohoutek System - more nebulae then galaxy

Q - Quasar - active galaxy emiting radio waves

QSO - Quasi Stellar Object - quasar without the radio

However I cannot find information on these and I do hope you can help.
Where possible I will give examples:

3C - Celestial Candidate Companion??? - can't seem to confirm 3C9, 3C68.1

OH - ??? - OH471

OQ - ??? - OQ172

PG - ??? - PG 1247+26

PHL - ??? - PHL957, PHL5200

So could you please help?