C/1984 W2 Hartley

Solar System
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Planetology
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C/1984 W2 Hartley

General description

Comet C/1984 W2 was discovered by Malcolm Hartley (1.2-m Schmidt telescope at Siding Spring) on 17 November 1984 (IAUC 4015), more than ten months before its perihelion passage. The comet was last seen on 18 May 1988.

The comet made its closest approach to the Earth on 11 December 1984 (3.89 au), that was three weeks after its discovery; in the next opposition the comet has closest approach to the Earth within 4.00 au (on 19 October 1985).

Solution given below is based on data span over 3.50 yr in the range of heliocentric distances: 4.80 au – 4.00 au (perihelion) – 8.52 au.

Comet suffered small planetary perturbations during its passage through the planetary system but these perturbations lead to escape of the comet from the solar system.

Figure caption: Time distribution of positional observations with corresponding heliocentric (red curve) and geocentric (green curve) distance at which they were taken. The horizontal dotted line shows the perihelion distance for a given comet whereas vertical dotted line — the moment of perihelion passage.

SSDP Cometary Note C1984W2N2-001

Comet C/1984 W2 Hartley

number of observations	54
number of residuals	107
data interval	1984 Nov. 17 — 1988 May 18
rms [arcsec]	1.87
orbit quality class	1a

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	19850912.0	= JD 2446320.5
time of perihelion passage (TT)	19850928.377250	± 0.006835
perihelion distance	4.00019640	± 0.00003608
eccentricity	0.99956150	± 0.00003854
argument of perihelion [deg]	255.267920	± 0.001006
longitude of the ascending node [deg]	250.208162	± 0.000101
inclination [deg]	89.327140	± 0.000096
inverse semimajor axis [10^-6 au^-1]	109.62	± 9.64

Nongravitational parameters [10^-8 au/day²]

A₁ = 36844 ± 23157

A₂ = 0.0 (assumed)

A₃ = 0.0 (assumed)

Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.

Figure caption: Six 2D-projections of the 6D space of original swarm (5001 VCs) of C/1984 W2. Each density map is given in logarithmic scale presented on the right in the individual panel.
The same figure in the new window

Original orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT)	16820212
time of perihelion passage (TT)	19850929.038315	± 0.014076
perihelion distance	4.00453691	± 0.00004945
eccentricity	0.99991890	± 0.00003430
argument of perihelion [deg]	255.286662	± 0.002360
longitude of the ascending node [deg]	250.227075	± 0.000102
inclination [deg]	89.263792	± 0.000096
inverse semimajor axis [10^-6 au^-1]	20.25	± 8.56

Note: Values of uncertainties of original/future orbital elements were derived using a swarm of 5001 osculating orbits of VCs (including the nominal osculating orbit given above) for original/future orbital evolution calclulations and then by fitting the distribution of a given orbital element of original/future swarm of VCs to Gaussian distribution.

Original barycentric positions and velocities of 5001 VCs at 250 au from the Sun are given here (data format), i.e. before entering the planetary zone.

Future orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT)	22881102
time of perihelion passage (TT)	19850930.147908	± 0.005057
perihelion distance	3.99720363	± 0.00004937
eccentricity	1.00012613	± 0.00003425
argument of perihelion [deg]	255.274852	± 0.001094
longitude of the ascending node [deg]	250.173500	± 0.000102
inclination [deg]	89.247736	± 0.000096
inverse semimajor axis [10^-6 au^-1]	-31.55	± 8.57