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
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting NO
number of residuals 2285
RMS [arcseconds] 0.48
orbit quality class 3a
orbital elements (heliocentric ecliptic J2000)
Epoch 2002 10 01
perihelion date 2002 10 02.00084116 ± 0.00154291
perihelion distance [au] 0.77591871 ± 0.00002682
eccentricity 0.99983474 ± 0.00007947
argument of perihelion [°] 105.964283 ± 0.002227
ascending node [°] 321.031220 ± 0.000985
inclination [°] 73.112847 ± 0.001446
recip semi-major axis [10-6 au-1] 212.98 ± 102.42
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] 7.5313 ± 0.7381
A2 [10-8au\day-2] 0.77826 ± 0.51416
A3 [10-8au\day-2] 0 (assumed)
m -2.15
n 5.093
k -4.6142
r0 [au] 2.808
α 0.1113