C/2004 T3 Siding Spring

Solar System
Dynamics &
Planetology
Group

General description

C/2004 T3 was discovered by R. McNaught on images from the Siding Spring 0.5m Uppsala Schmidt on 12 October 2004. Next days, its cometary apperance was confirmed by observers [IAUC 8421, 2004 October 21].

This comet made its closest approach to Earth on 19 July 2003 (8.611 au), three months after perihelion.

Solution given below is based on data span over 1.3 yr in a range of heliocentric distances from 9.40 au to 10.6 au.

Comet suffered a very slight planetary perturbations during its passage through the planetary 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 C2004T3A2-001

Comet C/2004 T3 Siding Spring

number of observations	109
number of residuals	209
data interval	2004 Oct. 12 — 2006 Jan. 31
rms [arcsec]	0.44
orbit quality class	1a

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20030501.0	= JD 2452760.5
time of perihelion passage (TT)	20030415.234572	± 0.024763
perihelion distance	8.86450665	± 0.00008577
eccentricity	0.99749028	± 0.00003702
argument of perihelion [deg]	259.677146	± 0.001656
longitude of the ascending node [deg]	50.392989	± 0.000134
inclination [deg]	71.959969	± 0.000050
inverse semimajor axis [10^-6 au^-1]	283.12	± 4.17

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/2004 T3. 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)	16901227
time of perihelion passage (TT)	20030414.895405	± 0.024434
perihelion distance	8.86554953	± 0.00008464
eccentricity	0.99959502	± 0.00003724
argument of perihelion [deg]	259.686943	± 0.001643
longitude of the ascending node [deg]	50.389055	± 0.000134
inclination [deg]	71.923588	± 0.000050
inverse semimajor axis [10^-6 au^-1]	45.68	± 4.20

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)	23151122
time of perihelion passage (TT)	20030416.040415	± 0.024562
perihelion distance	8.86447368	± 0.00008464
eccentricity	0.99933897	± 0.00003725
argument of perihelion [deg]	259.687490	± 0.001642
longitude of the ascending node [deg]	50.384035	± 0.000134
inclination [deg]	71.931989	± 0.000050
inverse semimajor axis [10^-6 au^-1]	74.57	± 4.20