C/1962 C1 Seki-Lines
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Comet C/1962 C1 was independently discovered on February 4, 1962, by Tsutomu Seki and Richard Lines. It is noteworthy due to its very small perihelion distance, q = 0.031 au, and the fact that, despite such a close approach to the Sun during perihelion passage, it survived. In March/April 1962, around the time of perihelion, it became bright enough to later earn the designation Great Comet of 1962. At the end of May, it entered solar conjunction and was not seen again until late October 1962. It was last observed in late January 1963; despite attempts, it was not recovered in February.
Solutions given here are based on data span over 0.96 yr around the perihelion (0.0314 au from the Sun) in a range of heliocentric distances from 1.53 au (pre-perihelion) to 4.88 au (post-perihelion).
Comet had its closest approach to the Earth on 1962, February 26 (0.618 au), that is about a a three weeks after its discovery and a month before perihelion passage.
The Minor Planet Center (MPC) lists 32 observations made at the Naval Observatory Flagstaff Station (code: 689); however, provides a gravitational (GR) orbit based on 92 observations over interval from February 7, 1962 to January 25, 1963.
For the purposes of the CODE Catalogue, a total of 162 observations from 14 observatories were collected from the literature. Based on this dataset, after applying selection and weighting, a purely gravitational orbit (GR, solution 'a5') was obtained. However, it was not possible to derive a non-gravitational (NG) orbit with satisfactorily constrained non-gravitational parameters. Nevertheless, by selecting only observations with weights above average (from four observatories, codes: 35, 415, 689, 754), both GR ('b5') and NG ('bn') solutions could be determined. Moreover, the root-mean-square (rms) residuals decreased significantly, from 2.26 arcseconds (GR orbit) to 1.47 arcseconds (NG orbit). For comparative purposes with JPL (which lists a GR orbit based on 32 observations – apparently those publicly available via the MPC; as on May 30, 2025), GR and NG orbits based on the 33 observations from the Naval Observatory Flagstaff Station are also provided ('f5' and 'fn').
Based on the GR solutions, one might infer that this is an Oort spike comet. However, both NG solutions suggest significantly smaller original semi-major axes around 3,300 au ('bn' and 'fn').
Positional observations
Solutions given here are based on data span over 0.96 yr around the perihelion (0.0314 au from the Sun) in a range of heliocentric distances from 1.53 au (pre-perihelion) to 4.88 au (post-perihelion).
Comet had its closest approach to the Earth on 1962, February 26 (0.618 au), that is about a a three weeks after its discovery and a month before perihelion passage.
The Minor Planet Center (MPC) lists 32 observations made at the Naval Observatory Flagstaff Station (code: 689); however, provides a gravitational (GR) orbit based on 92 observations over interval from February 7, 1962 to January 25, 1963.
For the purposes of the CODE Catalogue, a total of 162 observations from 14 observatories were collected from the literature. Based on this dataset, after applying selection and weighting, a purely gravitational orbit (GR, solution 'a5') was obtained. However, it was not possible to derive a non-gravitational (NG) orbit with satisfactorily constrained non-gravitational parameters. Nevertheless, by selecting only observations with weights above average (from four observatories, codes: 35, 415, 689, 754), both GR ('b5') and NG ('bn') solutions could be determined. Moreover, the root-mean-square (rms) residuals decreased significantly, from 2.26 arcseconds (GR orbit) to 1.47 arcseconds (NG orbit). For comparative purposes with JPL (which lists a GR orbit based on 32 observations – apparently those publicly available via the MPC; as on May 30, 2025), GR and NG orbits based on the 33 observations from the Naval Observatory Flagstaff Station are also provided ('f5' and 'fn').
Based on the GR solutions, one might infer that this is an Oort spike comet. However, both NG solutions suggest significantly smaller original semi-major axes around 3,300 au ('bn' and 'fn').
Positional observations
| solution description | ||
|---|---|---|
| number of observations | 64 | |
| data interval | 1962 02 07 – 1963 01 25 | |
| data type | perihelion within the observation arc (FULL) | |
| data arc selection | entire data set (STD) | |
| range of heliocentric distances | 1.53 au – 0.03 au (perihelion) – 4.88 au | |
| type of model of motion | NS - non-gravitational orbits for standard g(r) | |
| data weighting | YES | |
| number of residuals | 124 | |
| RMS [arcseconds] | 1.47 | |
| orbit quality class | 2a | |
| orbital elements (heliocentric ecliptic J2000) | ||
|---|---|---|
| Epoch | 1962 04 06 | |
| perihelion date | 1962 04 01.66352926 | ± 0.00006870 |
| perihelion distance [au] | 0.03139924 | ± 0.00000184 |
| eccentricity | 1.00001526 | ± 0.00000390 |
| argument of perihelion [°] | 11.475885 | ± 0.001116 |
| ascending node [°] | 304.676719 | ± 0.000526 |
| inclination [°] | 65.011978 | ± 0.000466 |
| reciprocal semi-major axis [10-6 au-1] | -486.03 | ± 124.23 |
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/day2] | -0.60837 | ± 0.36851 |
| A2 [10-8au/day2] | 0.045887 | ± 0.005439 |
| A3 [10-8au/day2] | 0.65807 | ± 0.25897 |
| m | -2.15 | |
| n | 5.093 | |
| k | -4.6142 | |
| r0 [au] | 2.808 | |
| α | 0.1113 | |