Harford County Astronomical Society

Glossary

Definitions

NCP : North Celestial Pole

RA : Right ascension: East-West Dec : Declination: North-South

RA 18h 36.9m (18 37) Dec +38d 47m (+38.7) Numbers in parentheses (*** ) are those presented in the DSC display.

LY : Light Year; a measure of distance(distance light travels in one year through a vacuum)5,878,000,000,000 miles

AU : Astronomical Unit(mean distance from the Earth to the Sun) 93,000,000 miles

Parsec: Par(alax) Sec(ond); a measure of distance; 1 pc=3.261 LY=206,265AU

pc, kpc: parsec, kiloparsec

DS : Double star Trip : triple Mult : multiple *: Star

V : variable star RV : red variable

OC : Open cluster GC : globular cluster AS: Asterism

PN : Planetary nebula EN : Emission nebula RN : reflection nebula

SG : Spiral galaxy EG : eliptical galaxy PG : Peculiar Galaxy IG : Irregular Galaxy

FOV : Field Of View DSO : Deep Sky Object NEV : Naked Eye Visible AV : Averted Vision

Observing Club designations

AL : Astronomical League DS : Double Star Club UC : Urban Club BMC : Binocular Messier Club

M-*** : Messier Club object H-**-** : Herschel 400 object

Binary star terminology:

A: Primary B: Secondary C: Third star and so on

h: hours m: arcminutes s: arcseconds d: degrees

1h = 60 arcminutes 1m = 60 arcseconds therefore 1h = 3,600 arcseconds (60 x 60)

Sep: separation of the components in arcseconds

Pa: Position angle of the two stars measured counterclockwise from North

Comes (pronounced: combs or comez): Traditional label for the secondary members of a true binary star system

Color Difference : (0-6) in the last column; Determined by how far apart the two components are on the standard scale of spectral classification: O-B-A-F-G-K-M ( Oh Be A Fine Girl Kiss Me )

Catalogs

Double Star

S STF F.G.W. Von Struve Dorpat Catalog (1827)

SI F.G.W. Von Struve First Supplement

S II Wilhelm Struve Second supplement

OS STT Otto Wilhelm Von Struve Pulkovo Catalog (1843, revised 1850)

HN H William Herschel

h HJ John Herschel

Kr KR A. Kruger

b BU S.W. Burnham

Kui G. Kuiper

Wnc Winneke

HD Henry Draper

A ADS R.G. Aitken

AGC AGC Alvin G. Clark

B B Willem H. van den Bos (1896-1974)

WDS Washington Double Star Survey, US Naval Observatory

Eng English

s,h SHJ James Smith and John Herschel (1874, Deep Sky Objects)

M Charles Messier, "Nebulae and Star Clusters", (1781)

NGC "New General Catalog of Nebulae and Clusters of Stars" (1888)

Mel Philibert Jacques Melotte (1880-1961) Clusters

Stock Jurgen Stock Clusters

CR

Col Collinder

Groom Groombridge

Dol Dolidze

Ced Cederblad

IC Index Catalog

Bayer Designations

English Greek

a A a A alpha

b B b B beta

g G g G gamma

d D d D delta

e E e E epsilon

z Z z Z zeta

h H h H eta

q Q q Q theta

i I i I iota

k K k K kappa

l L l L lambda

m M m M mu

n N n N nu

x X x X xi

o O o O omicron

p P p P pi

r R r R rho

s S s S sigma

t T t T tau

u U u U upsilon

f F f F phi

c C c C chi

y Y y Y psi

w W w W omega ------------------------------------------------------------------------------------------------------------------------------------------------------------------

Planetary Symbols

Planet Symbol English

Sol A A

Luna K K

Mercury B B

Venus C C

Earth D D

Mars E E

Jupiter F F

Saturn G G

Uranus H H

Neptune I I

Pluto J J