C/1990 M1 McNaught-Hughes
more info
In IAU Circ. No 5036, Robert H. McNaught reported his discovery of a comet on a U.K. Schmidt Telescope R plate taken by Shaun M. Hughes on 19 June at Siding Spring.At the moment of discovery, this comet was about 8.5 months before its perihelion passage.This comet was last observed in mid-June 1991.
Comet had its closest approach to the Earth on 13 April 1991 (1.853 au), about 1.5 month after perihelion passage.
Solution given here is based on data spanning over 0.986 yr in a range of heliocentric distances: 3.72 au – 2.68 au (perihelion) – 2.90 au.
This Oort spike comet suffers small planetary perturbations during its passage through the planetary system; however, these perturbations lead to escape the comet on hyperbolic orbit from the planetary zone.
See also Królikowska 2020.

solution description
number of observations 50
data interval 1990 06 19 – 1991 06 14
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 3.72 au – 2.68 au (perihelion) – 2.9 au
detectability of NG effects in the comet's motion NG effects not determinable
type of model of motion GR - gravitational orbit
data weighting NO
number of residuals 95
RMS [arcseconds] 0.87
orbit quality class 1b
orbital elements (heliocentric ecliptic J2000)
Epoch 1991 03 05
perihelion date 1991 02 27.66398641 ± 0.00062964
perihelion distance [au] 2.68225974 ± 0.00000413
eccentricity 1.00122833 ± 0.00001528
argument of perihelion [°] 18.171187 ± 0.000163
ascending node [°] 233.206189 ± 0.000055
inclination [°] 132.77397 ± 0.000065
recip semi-major axis [10-6 au-1] -457.94 ± 5.70
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