Key to Geocentric Ephemeris of the Sun


An ephemeris is a table of values that gives the positions of astronomical objects in the sky over a range of times, while geocentric means "as seen from Earth's center." The following table is a key to the geocentric ephemeris of the Sun and includes a description of each column in the ephemeris tables.

Key to Geocentric Ephemeris of the Sun
Column Heading Definition/Description
1 Date
(0 DT)
Calendar Date (Gregorian).
All ephemeris positions are for 00:00:00 UTC
(Coordinated Universal Time).
2 JD
(2440000+)
Abbreviated Julian Day Number.
To convert to full Julian Day Number, add 2440000.
The Julian Day Number is defined as the number of days
elapsed since Greenwich Mean Noon on 0 January 4713 BCE.
3 App. GST Apparent Greenwich Mean Sidereal Time at 00:00:00 UTC
(Coordinated Universal Time).
4 Equation of
Time
The difference between apparent solar time and mean solar time.
5 Apparent
R.A.
Apparent Right Ascension of the Sun for the true equator
and equinox of date (hours, minutes, seconds).
6 Apparent
Declination
Apparent Declination of the Sun for the true equator
and equinox of date (degrees, arc-minutes, arc-seconds).
7 Distance Distance of the Sun from Earth in astronomical units
(1 a.u. = 149,597,871 km).
8 Ang.
Diam.
Apparent Angular Diameter of the Sun (arc-seconds).
9 Hel.
Lng.
Heliographic Longitude of the central point of the solar disk (degrees).
10 Hel.
Lat.
Heliographic Latitude of the central point of the solar disk (degrees).
11 P.A.
Axis
Position Angle of the Sun's rotation axis, measured eastwards (counter-clockwise) on the sky from the celestial north point of the solar disk (degrees).