C/2002 O4 Hoenig
more info
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 1148
data interval 2002 07 27 – 2002 09 08
data arc selection data generally limited to pre-perihelion (PRE)
range of heliocentric distances 1.43 au – 0.89au
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 NO
number of residuals 2281
RMS [arcseconds] 0.52
orbit quality class 2b
orbital elements (barycentric ecliptic J2000)
Epoch 1713 04 19
perihelion date 2002 10 01.52593397 ± 0.00020140
perihelion distance [au] 0.77700212 ± 0.00001088
eccentricity 1.00060443 ± 0.00002911
argument of perihelion [°] 105.941244 ± 0.001278
ascending node [°] 320.975252 ± 0.000311
inclination [°] 73.122806 ± 0.000471
reciprocal semi-major axis [10-6 au-1] -777.89 ± 37.45
file containing 5001 VCs swarm
2002o4pa.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.