C/2007 U1 LINEAR

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C/2007 U1 LINEAR

General description

Comet C/2007 U1 was discovered 9.5 months before perihelion passage and next observed 2.1 yr during three oppositions in a range of heliocentric distances: 4.28 au – 3.329 au (perihelion) – 5.36 au

Comet had its closest approach to Earth on 21 October 2008 (2.424 au, 2.5 months after perihelion).

C/2007 U1 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 C2007U1N2-001

Comet C/2007 U1 LINEAR

number of observations	896
number of residuals	1774
data interval	2007 Oct. 19 — 2009 Nov. 18
rms [arcsec]	0.41
orbit quality class	1a

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20080802.0	= JD 2454680.5
time of perihelion passage (TT)	20080807.052978	± 0.000318
perihelion distance	3.32916349	± 0.00000195
eccentricity	1.00141625	± 0.00000446
argument of perihelion [deg]	0.928036	± 0.000079
longitude of the ascending node [deg]	50.043066	± 0.000020
inclination [deg]	157.786884	± 0.000010
inverse semimajor axis [10^-6 au^-1]	-425.41	± 1.34

Nongravitational parameters [10^-8 au/day²]

A₁ = 685.490 ± 45.424

A₂ = -221.870 ± 89.191

A₃ = -172.210 ± 18.419

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 U1. 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)	17040617
time of perihelion passage (TT)	20080807.839153	± 0.000354
perihelion distance	3.33102874	± 0.00000234
eccentricity	0.99944731	± 0.00000390
argument of perihelion [deg]	0.975217	± 0.000078
longitude of the ascending node [deg]	50.000626	± 0.000034
inclination [deg]	157.779808	± 0.000015
inverse semimajor axis [10^-6 au^-1]	165.92	± 1.17

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/2007 U1. 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)	23110924
time of perihelion passage (TT)	20080807.586941	± 0.000682
perihelion distance	3.32889293	± 0.00000318
eccentricity	0.99975241	± 0.00001201
argument of perihelion [deg]	1.194660	± 0.000152
longitude of the ascending node [deg]	50.311821	± 0.000036
inclination [deg]	157.785855	± 0.000032
inverse semimajor axis [10^-6 au^-1]	74.37	± 3.61