Comets - abbreviations

T The date of perihelion passage of the comet. The time scale used for this is Terrestrial Dynamical Time (TDT).
q The distance of the comet from the Sun at the time of perihelion passage, in astronomical units (AU).
e The eccentricity of the comet's orbit. An eccentricity of 0.0 means that the orbit is circular, whilst a value of 1.0 indicates a parabola. The majority of comets have an eccentricity between 0 and 1.
w The argument of perihelion, in degrees.
W The longitude of the ascending node of the orbit, in degrees.
i The inclination of the orbit, in degrees.
Magnitude Parameters These numbers (H and G) are used to calculate the magnitude of the comet given its distance from the Earth and Sun. The actual magnitude is calculated using the formula

mag = H + 5*log10(delta) + 2.5*G*log10(r)

where "delta" is the distance of the comet from the Earth (in astronomical units) and "r" is the distance of the comet from the Sun (also in A.U.).