C/1993 A1 Mueller
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Comet C/1993 A1 was discovered on 2 January 1993 by Jean Mueller (Palomar Sky Survey II). Later, a prediscovery image of this comet taken on 26 November 1992 (Catalina Station, Tucson) was found.At the moment of discovery, this comet was a year before its perihelion passage and it was last observed in the mid-August 1994.
Comet had its closest approach to the Earth on 13 November 1993 (1.713 au), 2 months before its perihelion passage.
This is a comet with nongravitational effects strongly manifested in positional data fitting.
Preferred solution given here is based on data spanning over 1.72 yr in a range of heliocentric distances: 4.89 au – 1.94 au (perihelion) – 3.19 au.
This Oort spike comet suffers moderate planetary perturbations during its passage through the planetary system; these perturbations lead to escape the comet on hyperbolic orbit from the planetary zone.See also Królikowska 2020.

solution description
number of observations 658
data interval 1992 11 26 – 1994 01 08
data arc selection data generally limited to pre-perihelion (PRE)
range of heliocentric distances 4.89 au – 1.94au
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting YES
number of residuals 1306
RMS [arcseconds] 1.14
orbit quality class 1a
orbital elements (barycentric ecliptic J2000)
Epoch 1693 09 22
perihelion date 1994 01 13.87885886 ± 0.00053386
perihelion distance [au] 1.94260390 ± 0.00000379
eccentricity 0.99990632 ± 0.00000627
argument of perihelion [°] 130.671908 ± 0.000157
ascending node [°] 144.723868 ± 0.000054
inclination [°] 124.970565 ± 0.000046
reciprocal semi-major axis [10-6 au-1] 48.22 ± 3.23
file containing 5001 VCs swarm
1993a1pn.bmi
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.
Six 2D-projections of the 6D space of original swarm including 5001 VCs. Each density map is given in logarithmic scale presented on the right in the individual panel.