C/1997 BA6 Spacewatch
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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.
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 eight months before perihelion).
Solutions given here are based on data spanning over 7.68 yr in a range of heliocentric distances: 9.15 au – 3.44 au (perihelion) – 13.39 au.
This Oort spike comet suffers moderate planetary perturbations during its passage through the planetary system that lead to notable more tight future orbit (see future barycentric orbit).
See also Królikowska 2014 and Królikowska and Dybczyński 2017.

solution description
number of observations 529
data interval 1997 01 11 – 2004 09 15
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 9.15 au – 3.44 au (perihelion) – 13.4 au
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting NO
number of residuals 1054
RMS [arcseconds] 0.67
orbit quality class 1a+
orbital elements (heliocentric ecliptic J2000)
Epoch 1999 12 08
perihelion date 1999 11 27.56615100 ± 0.00033400
perihelion distance [au] 3.43630558 ± 0.00000451
eccentricity 0.99882316 ± 0.00000508
argument of perihelion [°] 285.935698 ± 0.000033
ascending node [°] 317.663829 ± 0.000010
inclination [°] 72.714861 ± 0.000022
recip semi-major axis [10-6 au-1] 342.47 ± 1.48
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
non-gravitational parameters
A1 [10-8au\day-2] 3341 ± 118
A2 [10-8au\day-2] 24.3 ± 54.1
A3 [10-8au\day-2] -29.8 ± 11.7
m -2.15
n 5.093
k -4.6142
r0 [au] 2.808
α 0.1113