C/1978 A1 West
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Comet C/1978 A1 was discovered on 12 January 1978, almost six months after its perihelion passage, and was last seen on 7 April 1978 [Kronk and Meyer, Cometography: Volume 5]; later few prediscovery measurements going back up to 30 March 1976 were found, that is 15.5 months before its perihelion passage (see figure).
The comet made its closest approach to the Earth on 8 May 1977 (4.71 au), that was seven months before its discovery; however, in its next opposition – three months after discovery – the comet approached minimal distance of 4.94 au from the Earth (on 10 April 1978).
Solution given here is based on data spanning over 3.24 yr in a range of heliocentric distances: 6.57 au – 5.61 au (perihelion) – 7.50 au.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system that lead to escape the comet from the planetary zone on a hyperbolic orbit (see future barycentric orbit).
See also Królikowska 2014 and Królikowska and Dybczyński 2017.
The comet made its closest approach to the Earth on 8 May 1977 (4.71 au), that was seven months before its discovery; however, in its next opposition – three months after discovery – the comet approached minimal distance of 4.94 au from the Earth (on 10 April 1978).
Solution given here is based on data spanning over 3.24 yr in a range of heliocentric distances: 6.57 au – 5.61 au (perihelion) – 7.50 au.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system that lead to escape the comet from the planetary zone on a hyperbolic orbit (see future barycentric orbit).
See also Królikowska 2014 and Królikowska and Dybczyński 2017.
| solution description | ||
|---|---|---|
| number of observations | 62 | |
| data interval | 1976 03 30 – 1979 06 26 | |
| data type | perihelion within the observation arc (FULL) | |
| data arc selection | entire data set (STD) | |
| range of heliocentric distances | 6.57 au – 5.61 au (perihelion) – 7.5 au | |
| detectability of NG effects in the comet's motion | NG effects not determinable | |
| type of model of motion | GR - gravitational orbit | |
| data weighting | YES | |
| number of residuals | 120 | |
| RMS [arcseconds] | 1.30 | |
| orbit quality class | 1a | |
| previous orbit statistics, both Galactic and stellar perturbations were taken into account | ||
|---|---|---|
| no. of returning VCs in the swarm | 4890 | * |
| no. of escaping VCs in the swarm | 111 | |
| no. of hyperbolas among escaping VCs in the swarm | 1 | |
| previous reciprocal semi-major axis [10-6 au-1] | 24.13 – 35.34 – 42.25 | R |
| previous perihelion distance [au] | 170 – 1100 – 2000 | R |
| previous aphelion distance [103 au] | 47 – 55 – 81 | R |
| time interval to previous perihelion [Myr] | 2.6 – 4.2 – 7.7 | R |
| percentage of VCs with qprev < 10 | 8 | |
| percentage of VCs with qprev > 20 | 92 | |
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.
| previous orbit statistics, here only the Galactic tide has been included | ||
|---|---|---|
| no. of returning VCs in the swarm | 4814 | * |
| no. of escaping VCs in the swarm | 187 | |
| no. of hyperbolas among escaping VCs in the swarm | 5 | |
| previous reciprocal semi-major axis [10-6 au-1] | 24.30 – 37.94 – 52.89 | R |
| previous perihelion distance [au] | 9.2 – 20 – 150 | R |
| previous aphelion distance [103 au] | 38 – 53 – 82 | R |
| time interval to previous perihelion [Myr] | 2.6 – 4.3 – 8.2 | R |
| percentage of VCs with qprev < 10 | 15 | |
| percentage of VCs with 10 < qprev < 20 | 35 | |
| percentage of VCs with qprev > 20 | 50 | |