C/1984 W2 Hartley
more info
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).
Solutions given here are based on data spanning over 3.50 yr in a range of heliocentric distances: 4.80 au – 4.00 au (perihelion) – 8.52 au.
This Oort spike comet suffers slight planetary perturbations during its passage through the planetary system but these perturbations can lead to escape of the comet from the solar system.
See also Królikowska 2014 and Królikowska and Dybczyński 2017.

solution description
number of observations 54
data interval 1984 11 17 – 1988 05 18
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 4.8 au – 4.00 au (perihelion) – 8.52 au
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting NO
number of residuals 107
RMS [arcseconds] 1.87
orbit quality class 1a
next orbit statistics, both Galactic and stellar perturbations were taken into account
no. of returning VCs in the swarm 0
no. of escaping VCs in the swarm 5001
no. of hyperbolas among escaping VCs in the swarm 4999 *
next reciprocal semi-major axis [10-6 au-1] -42.10 – -31.19 – -20.52
next perihelion distance [au] 220 – 240 – 270
synchronous stop epoch [Myr] 1.76 S
percentage of VCs with qnext > 20100
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.
next orbit statistics, here only the Galactic tide has been included
no. of returning VCs in the swarm 0
no. of escaping VCs in the swarm 5001
no. of hyperbolas among escaping VCs in the swarm 4999 *
next reciprocal semi-major axis [10-6 au-1] -41.59 – -30.73 – -20.11
next perihelion distance [au] 7.49 – 8.22 – 9.05
synchronous stop epoch [Myr] 1.78 S
percentage of VCs with qnext < 1099
percentage of VCs with 10 < qnext < 201