C/2009 UG<sub>89</sub> Lemmon

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C/2009 UG₈₉ Lemmon

General description

C/2009 UG₈₉ was discovered in October 2009 by A.D. Grauer as an apparently asteroidal object (Mt Lemmon); CCD images taken by observers in April 2010 revealed a cometary activity [IAUC 9141, 2010 April 27]. C/2009 UG₈₉ passed perihelion in December 2010 (see below).

This comet was followed by 2.5 yr during four oppositions in a range of heliocentric distances: 5.30 au – 3.931 au (perihelion) – 5.73 au.

C/2009 UG₈₉ had its closest approach to Earth on 23 July 2010 (3.253 au, almost five months before perihelion).

The comet passed close to Jupiter one year and three months before perihelion passage (0.499 au, 23 September 2009, one month before 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 C2009UGA5-001

Comet C/2009 UG₈₉ Lemmon

number of observations	988
number of residuals	1938
data interval	2009 Oct. 22 — 2012 Apr. 27
rms [arcsec]	0.43
orbit quality class	1a+

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20101230.0	= JD 2455560.5
time of perihelion passage (TT)	20101216.270246	± 0.000173
perihelion distance	3.93116688	± 0.00000113
eccentricity	1.00805713	± 0.00000183
argument of perihelion [deg]	60.653833	± 0.000029
longitude of the ascending node [deg]	321.008496	± 0.000008
inclination [deg]	130.100465	± 0.000007
inverse semimajor axis [10^-6 au^-1]	-2049.55	± 0.47

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/2009 UG₈₉. 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)	17051010
time of perihelion passage (TT)	20101215.717896	± 0.000175
perihelion distance	3.94331616	± 0.00000107
eccentricity	0.99935483	± 0.00000189
argument of perihelion [deg]	60.375110	± 0.000029
longitude of the ascending node [deg]	321.002838	± 0.000008
inclination [deg]	130.344573	± 0.000008
inverse semimajor axis [10^-6 au^-1]	163.61	± 0.48

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/2009 UG₈₉. 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)	22990218
time of perihelion passage (TT)	20101215.222787	± 0.000174
perihelion distance	3.93075375	± 0.00000120
eccentricity	1.00562933	± 0.00000185
argument of perihelion [deg]	60.568963	± 0.000029
longitude of the ascending node [deg]	321.037062	± 0.000008
inclination [deg]	130.123598	± 0.000007
inverse semimajor axis [10^-6 au^-1]	-1432.12	± 0.47

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.