General points: Most data is recorded to 2 DP’s, and either uses familiar Earth metrics and SI units, or arbitrary or relative measurements (e.g. ‘Sols’ for mass of a star).

The same format for data is attempted throughout, and should have similar layouts and tolerances.

Stars:

Temperature: The recorded reading is an approximation based on a moving average, in reality regions can vary greatly (over 200K) so this temperature is only as a guideline given at recording.

Luminosity is proportional to the surface radiative area, and the effective temperature (Stefan-Boltzmann law).

Wavelength, like temperature is a generated average, which for most purposes is unnecessarily precise, it is derived from Wien’s law.

Class relates to the method of categorizing stars on the Hertzsprung Russel diagram, which is still in common use amongst Earth’s astronomers.

Planets

Orbital period is displayed alternatively in hours, days and years (sidereal).

Mean orbital radius is again an approximation, precise perihelion and aphelion can be found in more detailed orbital analyses.

Radius is an approximation, but accounts for equatorial bulging.

Temperature is an approximation again from reflected radiation compared to absorption, on very hot slow rotating planets, the sun facing side is measured.

Rotational period is the same as ‘day’ length, the time taken for a rotation of 360 degrees on its axis.

Atmosphere

Each gas reading ceilings at 2 bar, so values of these are expressed ‘+’ this amount of atmosphere is rarely not encountered on terrestrial worlds.

The term ‘trace’ refers to a gas that makes up less than 0.1% of the atmospheric total.

Gas speed analysis

This data table provides speeds of gases compared to the bodies escape velocity (Escape velocity/ Root mean square speeds). The numbers reflects how easily a gas is retained by the body, a value of less than 1 means that gas is very easily lost, where as high values, say above twenty, mean that that particular gas remains trapped by that body over geological timescales.

Surface hydrosphere

This data table decides whether certain liquids can exist on the surface, these tables are also influenced by atmospheric pressure, liquids can't form in a vacuum. Liquids not only require suitable temperatures, but also suitable pressures, too low and liquids can not form, too high and supercritical states are produced.

Compositional analysis

These readings are arbitrary but reflect the relative abundances in the region of the planets formation. Values approaching one become initial abundant compounds, where as values above or below one mean that these compounds are predominantly found further in from the planet (values less than one), or further away from the sun (values greater than one). Though these values do not account for planetary migration.

Detailed orbital analysis

This data section aims to provide more precise information not already covered in briefer planetary and satellite descriptions

Eccentricity is calculated on a 0 -1 scale, most objects in regular orbits have very low eccentricities generally <0.05

Apoapsis / Periapsis, Aphelion/Perihelion, mark the points where the body is closest (Peri-) to Sun (-helion) or body (-apsis) or at its furthest distance (Ap- / Apo-)

The Barycentre is the mutual centre of gravity between two bodies, in most cases the barycentre of a large planet and a small moon will lie well within the sphere of the planet

Orbital inclination, the distance above or below a determined plane, either around a star or planet

Habitability

Planetary conditions give a subjective judgment on global climate, hot / cold etc.

Temperatures are global approximations, and show variance at extremes of orbit