C/2007 D1

Solar System
Dynamics &
Planetology
Group

C/2007 D1 LINEAR

General description

C/2007 D1 was discovered on 17 February 2007 by the LINEAR as an apparently asteroidal object, however quickly its cometary appearance was reported.

This comet made its closest approaches to Earth on 22 February (7.880 au, four months before perihelion) and 4 March 2008 (7.933 au, 8.5 months after perihelion).

Solution given below is based on data span over 6.2 yr in a range of heliocentric distances: 8.82 au – 8.794 au (perihelion) – 14.7 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 C2007D1A5-001

Comet C/2007 D1 LINEAR

number of observations	548
number of residuals	1061
data interval	2007 Feb. 17 — 2013 May 4
rms [arcsec]	0.45
orbit quality class	1a+

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20070629.0	= JD 2454280.5
time of perihelion passage (TT)	20070619.460865	± 0.002729
perihelion distance	8.79372556	± 0.00001369
eccentricity	1.00191986	± 0.00000846
argument of perihelion [deg]	340.159247	± 0.000141
longitude of the ascending node [deg]	171.098537	± 0.000008
inclination [deg]	41.450252	± 0.000013
inverse semimajor axis [10^-6 au^-1]	-218.32	± 0.96

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/2007 D1. 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)	16950515
time of perihelion passage (TT)	20070619.627616	± 0.002693
perihelion distance	8.79200698	± 0.00001358
eccentricity	0.99961354	± 0.00000832
argument of perihelion [deg]	340.120329	± 0.000140
longitude of the ascending node [deg]	171.125352	± 0.000008
inclination [deg]	41.426988	± 0.000014
inverse semimajor axis [10^-6 au^-1]	43.96	± 0.95

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)	23280626
time of perihelion passage (TT)	20070614.544250	± 0.002784
perihelion distance	8.78831161	± 0.00001367
eccentricity	0.99351095	± 0.00000831
argument of perihelion [deg]	339.973968	± 0.000144
longitude of the ascending node [deg]	171.029787	± 0.000008
inclination [deg]	41.507970	± 0.000014
inverse semimajor axis [10^-6 au^-1]	738.37	± 0.95