C/2007 Y1 LINEAR

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C/2007 Y1 LINEAR

General description

C/2007 Y1 was discovered on 16 December 2007 by the LINEAR as an apparently asteroidal object. Next, its cometary apperance was reported by several observers [IAUC 8904, 2007 December 18].

This comet made its closest approaches to Earth on 10 February 2008 (2.402 au), 1.3 month before perihelion.

Solution given below is based on data span over 0.38 yr in a narrow range of heliocentric distances: 3.46 au – 3.341 au (perihelion) – 3.37 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 C2007Y1A2-001

Comet C/2007 Y1 LINEAR

number of observations	209
number of residuals	415
data interval	2007 Dec. 16 — 2008 May 3
rms [arcsec]	0.61
orbit quality class	2a

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20080404.0	= JD 2454560.5
time of perihelion passage (TT)	20080319.334554	± 0.002282
perihelion distance	3.34090683	± 0.00001666
eccentricity	1.00074172	± 0.00004139
argument of perihelion [deg]	357.128047	± 0.000534
longitude of the ascending node [deg]	133.091508	± 0.000091
inclination [deg]	110.179814	± 0.000359
inverse semimajor axis [10^-6 au^-1]	-222.01	± 12.39

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 Y1. 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)	17050722
time of perihelion passage (TT)	20080318.752689	± 0.002305
perihelion distance	3.34342252	± 0.00001664
eccentricity	0.99988596	± 0.00004164
argument of perihelion [deg]	357.085840	± 0.000533
longitude of the ascending node [deg]	133.054139	± 0.000092
inclination [deg]	110.125744	± 0.000364
inverse semimajor axis [10^-6 au^-1]	34.11	± 12.46

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)	23131023
time of perihelion passage (TT)	20080319.404978	± 0.002263
perihelion distance	3.34318656	± 0.00001678
eccentricity	0.99904941	± 0.00004165
argument of perihelion [deg]	357.056538	± 0.000534
longitude of the ascending node [deg]	133.054513	± 0.000092
inclination [deg]	110.169228	± 0.000361
inverse semimajor axis [10^-6 au^-1]	284.34	± 12.46