C/2005 B1 Christensen

Solar System
Dynamics &
Planetology
Group

General description

C/2005 B1 was discovered by E. Christensen on 16 January 2005 on Catalina Sky Survey images and its cometary apperance was soon confirmed [IAUC 8466, 2005 January 17]. Next, 2004 FS₁₀₁ reported as asteroidal object by LINEAR and Spacewatch in March 2004 was identified with C/2005 B1 [IAUC 8469, 2005 January 19].

This comet made its closest approach to Earth on 30 September 2006 (3.003 au), seven months after perihelion.

Solution given below is based on data span over 3.6 yr in a range of heliocentric distances: 6.94 au – 3.205 au (perihelion) – 5.49 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 C2005B1N2-001

Comet C/2005 B1 Christensen

number of observations	1517
number of residuals	2985
data interval	2004 Mar. 18 — 2007 Nov. 3
rms [arcsec]	0.43
orbit quality class	1a+

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	20060306.0	= JD 2453800.5
time of perihelion passage (TT)	20060223.575863	± 0.000110
perihelion distance	3.20492463	± 0.00000121
eccentricity	1.00026916	± 0.00000160
argument of perihelion [deg]	103.183642	± 0.000024
longitude of the ascending node [deg]	195.556016	± 0.000004
inclination [deg]	92.551290	± 0.000011
inverse semimajor axis [10^-6 au^-1]	-83.98	± 0.50

Nongravitational parameters [10^-8 au/day²]

A₁ = 74.7 ± 12.6

A₂ = -77.72 ± 9.17

A₃ = -63.94 ± 4.66

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/2005 B1. 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)	17040109
time of perihelion passage (TT)	20060222.262070	± 0.000227
perihelion distance	3.20593580	± 0.00000162
eccentricity	0.99998720	± 0.00000195
argument of perihelion [deg]	103.106005	± 0.000054
longitude of the ascending node [deg]	195.570413	± 0.000012
inclination [deg]	92.497575	± 0.000012
inverse semimajor axis [10^-6 au^-1]	3.99	± 0.61

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)	23101218
time of perihelion passage (TT)	20060223.968560	± 0.000262
perihelion distance	3.20473676	± 0.00000163
eccentricity	0.99923378	± 0.00000209
argument of perihelion [deg]	103.142507	± 0.000064
longitude of the ascending node [deg]	195.599965	± 0.000010
inclination [deg]	92.535516	± 0.000017
inverse semimajor axis [10^-6 au^-1]	239.09	± 0.65