77P/Longmore
Periodic comet
From Wikipedia, the free encyclopedia
77P/Longmore is a periodic comet in the Solar System, with a period of 6.8 years. It is the only comet discovered by Australian astronomer, Andrew Jonathan Longmore.
Longmore's Comet imaged from the Zwicky Transient Facility on 27 April 2023 | |
| Discovery | |
|---|---|
| Discovered by | Andrew J. Longmore |
| Discovery site | Siding Spring Observatory |
| Discovery date | 10 June 1975 |
| Designations | |
| P/1975 L1, P/1981 A1 | |
| |
| Orbital characteristics[1][2] | |
| Epoch | 17 October 2024 (JD 2460600.5) |
| Observation arc | 49.37 years |
| Number of observations | 2,712 |
| Aphelion | 4.895 AU |
| Perihelion | 2.348 AU |
| Semi-major axis | 3.621 AU |
| Eccentricity | 0.35166 |
| Orbital period | 6.891 years |
| Inclination | 24.320° |
| 14.457° | |
| Argument of periapsis | 196.65° |
| Mean anomaly | 80.540° |
| Last perihelion | 3 April 2023 |
| Next perihelion | 18 February 2030[3] |
| TJupiter | 2.860 |
| Earth MOID | 1.338 AU |
| Jupiter MOID | 0.202 AU |
| Physical characteristics[4] | |
Mean radius | 1.66±0.12 km |
Mean density | 550±80 kg/m3 |
| Comet total magnitude (M1) | 9.2 |
| Comet nuclear magnitude (M2) | 13.3 |
Observational history
It was discovered by Andrew Jonathan Longmore on a photographic plate taken on 10 June 1975 at the 1.22m Schmidt telescope at Siding Spring Observatory, New South Wales, Australia. Its brightness was estimated at an apparent magnitude of 17. After further observations Brian G. Marsden was able to calculate the perihelion date at 4 November 1975 and the orbital period as 6.98 years.[5]
The next perihelion date was computed to be 21 October 1981. T. Seki of Geisei, Japan relocated the comet on 2 January 1981 with a brightness of magnitude 18. It has since been observed in 1988, 1995, 2002 and 2009.
On 17 October 1963, the comet had passed 0.1577 AU (23.59 million km; 14.66 million mi) from Jupiter.[1]
During the 2023 perihelion passage the comet brightened to about apparent magnitude 14–15.[2]
