component A of a double or multiple star

adj

adjacent

B

component B of a double or multiple star

B

(with number) Barnard's catalogue of dark nebula

C

component C of a multiple star

CC

concentration class for globular clusters, from I to XII

Cl

cluster(s)

cn*

central star of planetary nebula

d

degree

Dbl

double star

dl

dark lane in galaxy or emission nebula

DN

dark nebula

EN

emission nebula

G

galaxy (with type)

GC

globular cluster

IC

Index catalogue

-in

inch (as in "8-in", meaning a telescope of 8-inch aperture)

inv

involved

LMC

Large Magellanic Cloud

M

Messier catalogue

m

visual magnitude

mag

visual magnitude

Mlt

multiple star

[name]

the originator of a descriptive name

NE

visible with the unaided eye

Neb

nebula

NGC

New General Catalogue

OC

open cluster

OIII

An Oxygen III nebular filter is recommended

p

photographic magnitude

PN

planetary nebula

Ri

rich in stars

RN

reflection nebula

SMC

Small Magellanic Cloud

SNR

Supernova remnant

st

star(s)

UHC

A filter passing both OIII and Hydrogen Beta is recommended

Var

Variable Star

?

the author questions the NGC2000.0 visual magnitude