C/2002 O4 Hoenig
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Comet C/2002 O4 was discovered on 22 July 2002 by Sebastian Hoenig (Dossenheim, Germany), that is about two months before its perihelion passage. It was observed until 1 October 2002.
Observers reported that C/2002 O4  started to disintegrate a few days before the perihelion, then faded very rapidly prior to perihelion passage; and in mid-October 2002, it was no longer possible to see this comet. Sekanina (2002) speculated that the comet was undergoing a major outburst near the time of its discovery (27 July 2002) and that a major loss of mass triggered by this episode completed in mid-August. The data arc for this comet is extremely short (two months); however, NG effects are easy detectable in its motion.
Preffered solution given here is based on pre-perihelion data spanning over 0.118 yr in a range of heliocentric distances from 1.43 au to 0.895 au (8 September 2002).
Comet had its closest approach to the Earth on 10 August 2002 (0.650 au), about 2 weeks after its discovery.
The NG orbit obtained from the full data arc gives negative original 1/a, whereas the NG orbit derived using a shorter data arc (see preferred orbit) results in a closed original orbit with semimajor axis shorter than 5000 au, indicating that the orbit of this comet is poorly known.
See also Sekanina 2019 and Królikowska 2020.

solution description
number of observations 1217
data interval 2002 07 27 – 2002 10 01
data type observed only before perihelion (PRE)
data arc selection entire data set (STD)
range of heliocentric distances 1.43 au – 0.78 au (perihelion) – 0.77 au
detectability of NG effects in the comet's motion comet lost close to perihelion or split comet
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 2418
RMS [arcseconds] 0.52
orbit quality class 2a
orbital elements (barycentric ecliptic J2000)
Epoch 1713 07 08
perihelion date 2002 10 01.52581153 ± 0.00008454
perihelion distance [au] 0.77700885 ± 0.00000458
eccentricity 1.00062355 ± 0.00001291
argument of perihelion [°] 105.940448 ± 0.000543
ascending node [°] 320.975467 ± 0.000139
inclination [°] 73.123131 ± 0.000209
reciprocal semi-major axis [10-6 au-1] -802.50 ± 16.61
file containing 5001 VCs swarm
2002o4a1.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.