C/2008 FK75 Lemmon–Siding Spring

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C/2008 FK₇₅ Lemmon – Siding Spring

General description

C/2008 FK₇₅ was first discovered on 31 March 2008 in the course of the Mt.Lemmon Survey as an apparently asteroidal object. Next, independently was rediscovered by Siding Spring survey (again as apparently asteroidal) on 1 July 2008. Two days later, J. Young reported that images showed diffuse coma [IAUC 8958, 2008 July 7]; then other observers confirmed cometary appearance.

Observational arc of C/2008 FK₇₅ covered 5.6 yr in a range of heliocentric distances: 8.24 au – 4.511 au (perihelion) – 9.51 au.

Comet had its closest approach to Earth on 16 June 2010 (4.057 au, 2.5 months before perihelion).

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 C2008FKC6-001

Comet C/2008 FK₇₅ Lemmon – Siding Spring

number of observations	3702
number of residuals	7376
data interval	2008 Mar. 31 — 2013 Nov. 6
rms [arcsec]	0.48
orbit quality class

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20101011.0	= JD 2455480.5
time of perihelion passage (TT)	20100929.255454	± 0.000282
perihelion distance	4.51081691	± 0.00000120
eccentricity	1.00250978	± 0.00000130
argument of perihelion [deg]	80.420309	± 0.000042
longitude of the ascending node [deg]	218.268538	± 0.000005
inclination [deg]	61.175925	± 0.000003
inverse semimajor axis [10^-6 au^-1]	-556.39	± 0.29

Nongravitational parameters [10^-8 au/day²]

A₁ = 1.86120 ± 0.04767

A₂ = -0.52217 ± 0.06047

A₃ = 0.27512 ± 0.01110

where g(r)-like function (CO sublimation) were applied:

r₀ = 10.0

m = 2.0

n = 3.0

k = 2.6

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/2008 FK₇₅. 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)	17051229
time of perihelion passage (TT)	20100929.366429	± 0.000278
perihelion distance	4.50554277	± 0.00000122
eccentricity	0.99980678	± 0.00000131
argument of perihelion [deg]	80.520499	± 0.000042
longitude of the ascending node [deg]	218.228903	± 0.000005
inclination [deg]	61.190077	± 0.000003
inverse semimajor axis [10^-6 au^-1]	42.88	± 0.29

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/2008 FK₇₅. 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)	23140220
time of perihelion passage (TT)	20100930.240295	± 0.000281
perihelion distance	4.50753802	± 0.00000121
eccentricity	1.00033903	± 0.00000130
argument of perihelion [deg]	80.408981	± 0.000042
longitude of the ascending node [deg]	218.247732	± 0.000005
inclination [deg]	61.190648	± 0.000003
inverse semimajor axis [10^-6 au^-1]	-75.21	± 0.29

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.