C/1997 BA6 Spacewatch

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C/1997 BA₆ Spacewatch

General description

Comet C/1997 BA6 was discovered as an asteroidal object by the Spacewatch program on 31 January 1997 (with also prediscovery images on January 11) (IAUC 6561). In February, two independent groups on the basis of exposures with 2.4-m Hiltner Telescope at Kitt Peak and 2.2-m telescope on Mauna Kea detected coma around C/1997 BA6 (IAUC 6561).

At the moment of discovery the comet was almost three years before its perihelion passage. C/1997 BA6 was last seen on 15 September 2004.

The comet made its closest approach to the Earth on 27 July 2000 (3.21 au), that was eight months after perihelion passage, however in the previous opposition it was within 3.66 au on 20 March 1999 (about seven months before perihelion).

Solution given below is based on data span over 7.68 yr in the range of heliocentric distances: 9.15 au – 3.44 au (perihelion) – 13.39 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 C1997BAN1-001

Comet C/1997 BA₆ Spacewatch

number of observations	529
number of residuals	1054
data interval	1997 Jan. 11 — 2004 Sep. 15
rms [arcsec]	0.67
orbit quality class	1a+

Osculating orbital elements (heliocentric; ecliptic J2000.0)

Epoch (TT)	19991208.0	= JD 2451520.5
time of perihelion passage (TT)	19991127.566151	± 0.000334
perihelion distance	3.43630558	± 0.00000451
eccentricity	0.99882316	± 0.00000508
argument of perihelion [deg]	285.935698	± 0.000033
longitude of the ascending node [deg]	317.663829	± 0.000010
inclination [deg]	72.714861	± 0.000022
inverse semimajor axis [10^-6 au^-1]	342.47	± 1.48

Nongravitational parameters [10^-8 au/day²]

A₁ = 3341 ± 118

A₂ = 24.2 ± 54.1

A₃ = -29.8 ± 11.7

Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.

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.
Note: Epoch is given in a format: yyyymmdd.d, time of perihelion passage in a format of yyyymmdd.dddddd.

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/1997 BA₆. Each density map is given in logarithmic scale presented on the right in the individual panel.
The same figure in the new window

Original orbital elements (barycentric; at 250 au from the Sun)

Epoch (TT)	16970213
time of perihelion passage (TT)	19991128.142457	± 0.000636
perihelion distance	3.44037125	± 0.00000574
eccentricity	0.99989050	± 0.00000397
argument of perihelion [deg]	285.894624	± 0.000149
longitude of the ascending node [deg]	317.682671	± 0.000011
inclination [deg]	72.629264	± 0.000022
inverse semimajor axis [10^-6 au^-1]	31.83	± 1.15

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)	23070217
time of perihelion passage (TT)	19991128.384619	± 0.000943
perihelion distance	3.43278727	± 0.00000591
eccentricity	0.99861836	± 0.00000589
argument of perihelion [deg]	285.874864	± 0.000187
longitude of the ascending node [deg]	317.586592	± 0.000014
inclination [deg]	72.674074	± 0.000023
inverse semimajor axis [10^-6 au^-1]	402.48	± 1.72

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.