SYMBOLS

The following symbol set should be used in dialling equations wherever possible. In computer programs and spreadsheets, where Greek symbols cannot be used, the capitalised version should be used instead. The sign conventions and reference points for the various parameters are given in the main glossary.


Symbole Symboles

Signification

Dimensions

(a) Co-ordinates on the celestial sphere, etc.

RA

Ascension droite d'un corps céleste

angle or time

DELTA, DEC

declinaison du soleil (ou d'un autre corps céleste)

angle

ELON

longitude ecliptique d'un corps céleste

angle

ELAT

latitude ecliptique d'un corps céleste

angle

EPS

obliquité de ecliptique

angle

ec

EC

eccentricity of the Earth’s orbit

dimensionless

s

S

Sun's semi-diameter

angle

(b) Observer's local co-ordinates

LON

longitude (terrestrial) (positive west of Greenwich)

angle

PHI, Lat

latitude of a place

angle

h

HA

hour angle (p.m. hours give positive angles)

angle

A

AZ

azimuth of the sun (clockwise from S)

angle

a

ALT

altitude of the sun

angle

z

ZD

zenith distance

angle

PA

parallactic angle

angle

(c) Sundial parameters

d

DEC

declination of a wall (E negative, W positive)

angle

i

INC

inclination of the dial plate (horiz. to back of dial)

angle

v

V

angle between noon line and angle of greatest slope for a declining, inclining dial

angle

SH

SH

style height or angle from dial plane (note unusual use of "height")

angle

SD

SD

sub-style angle from noon line

angle

DL

DL

difference in longitude

angle

X

HLA

hour line angle from noon line (positive for pm)

angle

N

NH

nodus height above dial plate (or length of vertical style)

distance

(d) Time related

E

EoT

Equation of Time (as a time)

time

Ea

EoTA

Equation of Time (as an equivalent hour angle)

angle

t

T

time (subscript shows which system)

time

LAT

LAT or L.A.T.

Local Apparent Time

time

LMT

LMT

Local Mean Time (LAT corrected for EoT)

time

ST

ST

Standard Time (LMT corrected for longitude)

time

TDT

TDT

Terrestrial Dynamic Time

time

TZ

TZ

Time Zone number (integer)

dimensionless

tsr, tss

TSR, TSS

times of sunrise and sunset

time

JD

JD

the Julian Day number

days

SDT

sidereal time

time

ST

ST

standard time

time

ET

ET

ephemeris time (obsolete)

time

UT or UTC

UT

Universal Time (Co-ordinated)

time

GMT

GMT

Greenwich Mean Time

time

DST

DST

Daylight Saving Time

time

BST

BST

British Summer Time

time

(e) Co-ordinate systems

(x, y)

X, Y

cartesian co-ordinates of a point on the dial plane w.r.t. the origin. Optionally, (x, y, 0) in 3-D

length, length

R, THETA

polar co-ordinates of a point on a dial plane w.r.t. the origin

length, angle

hec

HEC

hectemoros angle

angle

hor

HOR

horarius angle

angle

(f) Miscellaneous

MU

refractive index

dimensionless

Ro

R0

angle of atmospheric refraction

angle

T

TEMP

temperature

Kelvin


Notes: is traditionally used for both terrestrial and ecliptic longitudes. In the rare cases where this could cause confusion, they should be denoted t and e, respectively.