USAAAO - Perturbation of Coordinates Information

Fundamentals of Astronomy Ch. 3

Period of Precession (years)

25765

Change of Ecliptic Longitude

dλ/dt = 50"/year

Dates of Sun Passage Through Capricornus

20 January → 16 February

Dates of Sun Passage Through Aquarius

16 February → 11 March

Dates of Sun Passage Through Pisces

11 March → 18 April

Dates of Sun Passage Through Aries

18 April → 13 May

Dates of Sun Passage Through Taurus

13 May → 21 June

Dates of Sun Passage Through Gemini

21 June → 20 July

Dates of Sun Passage Through Cancer

20 July → 10 August

Dates of Sun Passage Through Leo

10 August → 16 September

Dates of Sun Passage Through Virgo

16 September → 30 October

Dates of Sun Passage Through Libra

30 October → 23 November

Dates of Sun Passage Through Scorpius

23 November → 29 November

Dates of Sun Passage Through Ophiuchus

29 November → 17 December

Dates of Sun Passage Through Sagittarius

17 December → 20 January

Symbol of Capricornus

♑

Symbol of Aquarius

♒

Symbol of Pisces

♓,︎ ♈ for the vernal equinox

Symbol of Aries

♈

Symbol of Taurus

♉

Symbol of Gemini

♊

Symbol of Cancer

♋

Symbol of Leo

♌

Symbol of Virgo

♍

Symbol of Libra

♎

Symbol of Scorpius

♏

Symbol of Ophiuchus

⛎

Symbol of Sagittarius

♐

Vernal Equinox

March 21

Summer Solstice

June 21

Autumnal Equinox

September 23

Winter Solstice

December 22

Constant of Aberration

k = 20”

Diurnal Aberrartion

k_d = 0.3”

Refractive Index of Atmosphere at Sea Level

n_o = 1.0003

Angle of Deviation at the Horizon

R ≈ 34’

Range of the Ecliptic

22.1° < ε < 24.5°

Ecliptic Incline

ε = 23°27'

Period of Ecliptic Incline (years)

41000

Change of the Ecliptic Incline (J2000)

dε/dt = -47"/100 years

Range of Earth’s Orbital Eccentricity

0.000055 ≤ e ≤ 0.0679 (currently decreasing)

Period of Earth’s Orbital Eccentricty (years)

100000

Current Orbital Eccentricity

e = 0.0167