C/2005 EL173 LONEOS

Solar System
Dynamics &
Planetology
Group

C/2005 EL₁₇₃ LONEOS

General description

C/2005 EL₁₇₃ was discovered on 8 March 2005 by the LONEOS as an apparently asteroidal object in a retrograde orbit and semimajor axis of 36 au [MPEC 2005-F48, 2005 March 29]. Therefore it was initially classified as cubewano or scattered disc object in MPC. Its cometary apperance was reported by A. Fitzsimmons on 10 May 2005.

This comet made its closest approach to Earth on 4 January 2007 (3.310 au), two months before perihelion.

Solution given below is based on data span over 3.7 yr in a range of heliocentric distances: 7.12 au – 3.886 au (perihelion) – 6.45 au.

Comet suffered a very slight planetary perturbations during its passage through the planetary system, however these perturbations could move out this comet from the solar system (see below).

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 C2005ELN2-001

Comet C/2005 EL₁₇₃ LONEOS

number of observations	317
number of residuals	632
data interval	2005 Mar. 3 — 2008 Nov. 17
rms [arcsec]	0.36
orbit quality class	1a+

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20070301.0	= JD 2454160.5
time of perihelion passage (TT)	20070305.871906	± 0.000180
perihelion distance	3.88631166	± 0.00000283
eccentricity	1.00333283	± 0.00000329
argument of perihelion [deg]	261.493679	± 0.000034
longitude of the ascending node [deg]	344.796425	± 0.000009
inclination [deg]	130.679610	± 0.000008
inverse semimajor axis [10^-6 au^-1]	-857.58	± 0.84

Nongravitational parameters [10^-8 au/day²]

A₁ = 6602 ± 773

A₂ = -7175 ± 496

A₃ = 0.0 (assumed)

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/2005 EL₁₇₃. 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)	17030623
time of perihelion passage (TT)	20070305.845896	± 0.000536
perihelion distance	3.88759263	± 0.00000374
eccentricity	0.99982582	± 0.00000387
argument of perihelion [deg]	261.492080	± 0.000096
longitude of the ascending node [deg]	344.763229	± 0.000009
inclination [deg]	130.759788	± 0.000008
inverse semimajor axis [10^-6 au^-1]	44.81	± 0.99

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)	23100313
time of perihelion passage (TT)	20070305.948169	± 0.000563
perihelion distance	3.88766749	± 0.00000364
eccentricity	1.00007433	± 0.00000354
argument of perihelion [deg]	261.461335	± 0.000111
longitude of the ascending node [deg]	344.826942	± 0.000009
inclination [deg]	130.732213	± 0.000008
inverse semimajor axis [10^-6 au^-1]	-19.12	± 0.91

Future barycentric positions and velocities of 5001 VCs at 250 au from the Sun are given here (data format), i.e. after leaving the planetary zone.