C/1973 W1 Gibson

Solar System
Dynamics &
Planetology
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C/1973 W1 Gibson

General description

Comet C/1973 W1 was discovered on 24 November 1973, about 3.5 months after perihelion passage, and was last seen on 11 October 1974 [Kronk and Meyer, Cometography: Volume 5]

The comet made its closest approach to the Earth on 19 October 1973 (3.372 au), 1.2 months before discovery.

Solution given below is based on data span over 0.86 yr in a range of heliocentric distances from 3.97 au to 5.29 au.

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 C1973W1A1-001

Comet C/1973 W1 Gibson

number of observations	22
number of residuals	43
data interval	1973 Nov. 30 — 1974 Oct. 11
rms [arcsec]	0.72
orbit quality class	1b

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	19730826.0	= JD 2441920.5
time of perihelion passage (TT)	19730809.894467	± 0.006669
perihelion distance	3.84227589	± 0.00008706
eccentricity	1.00063440	± 0.00004761
argument of perihelion [deg]	221.260826	± 0.002045
longitude of the ascending node [deg]	244.600667	± 0.000280
inclination [deg]	108.066889	± 0.000095
inverse semimajor axis [10^-6 au^-1]	-165.11	± 12.39

Notes: 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/1973 W1. Each density map is given in logarithmic scale presented on the right in the individual panel.
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Original orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT)	16690819
time of perihelion passage (TT)	19730810.055023	± 0.006665
perihelion distance	3.84026288	± 0.00008612
eccentricity	0.99972033	± 0.00004727
argument of perihelion [deg]	221.390019	± 0.002037
longitude of the ascending node [deg]	244.629964	± 0.000278
inclination [deg]	108.049930	± 0.000094
inverse semimajor axis [10^-6 au^-1]	72.83	± 12.31

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)	22750624
time of perihelion passage (TT)	19730810.219208	± 0.006610
perihelion distance	3.84312446	± 0.00008654
eccentricity	1.00041071	± 0.00004732
argument of perihelion [deg]	221.296365	± 0.002035
longitude of the ascending node [deg]	244.622483	± 0.000278
inclination [deg]	108.018234	± 0.000096
inverse semimajor axis [10^-6 au^-1]	-106.87	± 12.31