A Dreyer description is a standardized abbreviation "shorthand" used by astronomers to describe in some detail an object's appearance and charactoristics, to assist observers in recognizing an item of interest or describing observations without lengthy prose. These codes are based on Dreyer's original object descriptions, modified as necessary to fit within simple text characters. Each description will generally consist of a series of comma-separated abbreviations.
Ab
alm
am
app
att
b
B
be
bf
biN
bn
bp
bs
c
C
C.G.H
ch
Cl
co
com
cont
d
D
def
dif
diffic
dist
e
E
ee
er
alm
am
app
att
b
B
be
bf
biN
bn
bp
bs
c
C
C.G.H
ch
Cl
co
com
cont
d
D
def
dif
diffic
dist
e
E
ee
er
about
almost
among
appended
attached
brighter
bright
between
brightest towards the following side
binuclear
brightest towards the north side
brightest towards the preceding side
brightest towards the south side
considerably
compressed
Cape of Good Hope
chevelure
cluster
coarse, coarsely
cometic
in contact
diameter
double
defined
diffused
difficult
distance or distant
extremely, excessively
extended
most extremely
easily resolvable
almost
among
appended
attached
brighter
bright
between
brightest towards the following side
binuclear
brightest towards the north side
brightest towards the preceding side
brightest towards the south side
considerably
compressed
Cape of Good Hope
chevelure
cluster
coarse, coarsely
cometic
in contact
diameter
double
defined
diffused
difficult
distance or distant
extremely, excessively
extended
most extremely
easily resolvable
exc
f
F
g
gr
i
iF
inv
l
L
m
M
mm
mn
n
N
neb
nf
np
nr
p
p
P
pg
pm
ps
quad
quar
r
R
Ri
f
F
g
gr
i
iF
inv
l
L
m
M
mm
mn
n
N
neb
nf
np
nr
p
p
P
pg
pm
ps
quad
quar
r
R
Ri
excentric
following
faint
gradually
group
irregular
irregular figure
involved,involving
little,long
large
much
middle, or in the middle
mixed magnitudes
milky nebulosity
north
Nucleus, or to a Nucleus
nebula
north following
north preceding
near
pretty (before F,B,L,S)
preceding
poor
pretty gradually
pretty much
pretty suddenly
quadrilateral
quartile
resolvable (mottled,not resolved)
round
rich
following
faint
gradually
group
irregular
irregular figure
involved,involving
little,long
large
much
middle, or in the middle
mixed magnitudes
milky nebulosity
north
Nucleus, or to a Nucleus
nebula
north following
north preceding
near
pretty (before F,B,L,S)
preceding
poor
pretty gradually
pretty much
pretty suddenly
quadrilateral
quartile
resolvable (mottled,not resolved)
round
rich
rr
RR
rrr
s
s
S
sc
sev
sf
sh
sm
sp
st
st 9
st 9 13
stell
susp
trap
triN
v
var
vv
"
'
!
!!
!!!
()
*
**
***
RR
rrr
s
s
S
sc
sev
sf
sh
sm
sp
st
st 9
st 9 13
stell
susp
trap
triN
v
var
vv
"
'
!
!!
!!!
()
*
**
***
partially relolved, some stars seen
exactly round
well resolved, clearly consisting of stars
suddenly
south
small
scattered
several
south following
shaped
smaller
south preceding
stars
stars from the 9th magnitude downwards
stars from the 9th to 13th magnitude
stellar
suspected
trapezium
trinuclear
very
variable
very, very
arc seconds (two "not-equals" in published catalog)
arc minutes (one "not-equals" in published catalog)
remarkable
very remarkable
a magnificent or otherwise interesting object
items questioned by Dreyer enclosed in parentheses
a star: *10, a star of 10th magnitude
double star
triple star
exactly round
well resolved, clearly consisting of stars
suddenly
south
small
scattered
several
south following
shaped
smaller
south preceding
stars
stars from the 9th magnitude downwards
stars from the 9th to 13th magnitude
stellar
suspected
trapezium
trinuclear
very
variable
very, very
arc seconds (two "not-equals" in published catalog)
arc minutes (one "not-equals" in published catalog)
remarkable
very remarkable
a magnificent or otherwise interesting object
items questioned by Dreyer enclosed in parentheses
a star: *10, a star of 10th magnitude
double star
triple star
As an example, consider the Dreyer code for the log entry of galaxy NGC 1532:
| / | NGC-1532 | 04h12m04s | -32°52'26'' | Eri | GXY | 11 | 5.6 | NGC1532 | B, vL, vmE 32deg, psmbM |
Its description would be read as:Bright, very Large, very much Extended along the 32 degree axis, proceeding south much brighter in the Middle
References used to research information for this page:
The NGC/IC Project website. Unfortunately, this site is currently unavailable, although archives of earlier versions can be found at
http://web.archive.org/web/*/http://www.ngcic.com
Documentation for the Computer-Readable Version of NGC 2000.0, by Wayne H. Warren Jr. (Edited by R.W. Sinnott 1988) December 1989, available at
http://www.maa.clell.de/Cat/Vol1/NGC2000/ngc2000.doc
The NGC on the Net, with links to The Interactive NGC Catalog Online by Hartmut Frommert of SEDS, and The NGC/IC Project
http://obs.nineplanets.org/ngc.html
The NGC/IC Project website. Unfortunately, this site is currently unavailable, although archives of earlier versions can be found at
http://web.archive.org/web/*/http://www.ngcic.com
Documentation for the Computer-Readable Version of NGC 2000.0, by Wayne H. Warren Jr. (Edited by R.W. Sinnott 1988) December 1989, available at
http://www.maa.clell.de/Cat/Vol1/NGC2000/ngc2000.doc
The NGC on the Net, with links to The Interactive NGC Catalog Online by Hartmut Frommert of SEDS, and The NGC/IC Project
http://obs.nineplanets.org/ngc.html
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Dreyer Descriptions