C/1991 C3 McNaught-Russell

Solar System
Dynamics &
Planetology
Group

General description

Comet C/1991 C3 was discovered on February 12, 1991 (almost four months after perihelion passage), however two days later the prediscovery observation taken on January 26 was found [IAUC 5189, 15 Feb]. The comet was observed 1.3 yr in the range of heliocentric distances from 4.84 au to 6.41 au with almost one-year gap between 16 May 1991 and 30 April 1992.

C/1991 C3 made its closest approach to Earth on 11 March 1991 (3.98 au), that was one months after its discovery.

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 C1991C3A1-001

Comet C/1991 C3 McNaught-Russell

number of observations	42
number of residuals	82
data interval	1991 Jan. 26 — 1992 Apr. 30
rms [arcsec]	0.96
orbit quality class	1b

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	19901105.0	= JD 2448200.5
time of perihelion passage (TT)	19901018.197249	± 0.009248
perihelion distance	4.77707372	± 0.00005293
eccentricity	1.00174603	± 0.00010724
argument of perihelion [deg]	320.886310	± 0.001085
longitude of the ascending node [deg]	161.709637	± 0.000174
inclination [deg]	113.430375	± 0.000389
inverse semimajor axis [10^-6 au^-1]	-365.50	± 22.44

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/1991 C3. 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)	16831224
time of perihelion passage (TT)	19901018.626787	± 0.009266
perihelion distance	4.77416391	± 0.00005344
eccentricity	0.99917740	± 0.00010632
argument of perihelion [deg]	320.983556	± 0.001101
longitude of the ascending node [deg]	161.703733	± 0.000174
inclination [deg]	113.445718	± 0.000381
inverse semimajor axis [10^-6 au^-1]	172.30	± 22.27

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.

Figure caption: Six 2D-projections of the 6D space of future swarm (5001 VCs) of C/1991 C3. Each density map is given in logarithmic scale presented on the right in the individual panel.
The same figure in the new window

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

Epoch (TT)	23131202
time of perihelion passage (TT)	19901016.798871	± 0.009585
perihelion distance	4.77139459	± 0.00005493
eccentricity	0.99323264	± 0.00010642
argument of perihelion [deg]	320.741939	± 0.001141
longitude of the ascending node [deg]	161.716960	± 0.000177
inclination [deg]	113.668530	± 0.000370
inverse semimajor axis [10^-6 au^-1]	1418.32	± 22.32