 Comet Herschel–Rigollet photographed byFerdinand Quénisset on 14 August 1939 | |
| Discovery | |
|---|---|
| Discovered by | Caroline Herschel Roger Rigollet |
| Discovery date | 21 December 1788 28 July 1939 |
| Designations | |
| P/1788 Y1, P/1939 O1 | |
| 1788 II, 1939 VI, 1939h | |
| Orbital characteristics[4] | |
| Epoch | 5 August 1939 (JD 2429480.5) |
| Observation arc | 152 years |
| Number of observations | 75 |
| Aphelion | 56.939 AU |
| Perihelion | 0.748 AU |
| Semi-major axis | 28.844 AU |
| Eccentricity | 0.97405 |
| Orbital period | 155 years |
| Inclination | 64.207° |
| 355.98° | |
| Argument of periapsis | 29.298° |
| Mean anomaly | 359.97° |
| Last perihelion | 9 August 1939 |
| Next perihelion | 13 February 2092(MPC)[1] 17 February 2092(JPL)[2] 16 March 2092[3] |
| TJupiter | 0.644 |
| Comet total magnitude (M1) | 8.3 |
35P/Herschel–Rigollet is aperiodiccomet with anorbital period of 155 years and anorbital inclination of 64 degrees. It was discovered byCaroline Herschel (Slough,United Kingdom) on 21 December 1788. Given that the comet has a 155-year orbit involving asymmetric outgassing,[4] andastrometric observations in 1939 were not as precise as modern observations, predictions for the nextperihelion passage in 2092 vary by about a month.
Caroline Herschel first observed the comet on 21 December 1788 and it was observed later that night by her brotherWilliam Herschel who described it as looking like a brightnebula and about 5–6minutes in diameter, and much larger than theplanetary nebula,Messier 57.
Through December and January the comet was observed byNevil Maskelyne at theGreenwich Observatory and byCharles Messier at theParis Observatory. Maskelyne was the last observer of the comet, his final observation taking place on 5 February 1789.
Similar possibleorbits for the comet were calculated in 1789 byPierre Méchain and in 1922 byMargaretta Palmer. Palmer considered that the orbit which best fitted the observations was an elliptical one with aperiod of 1,066 years.
Roger Rigollet (Lagny,France) rediscovered the comet on 28 July 1939; it was described as diffuse and with amagnitude of 8.0. The sighting was confirmed the next day byAlfonso Fresa of theObservatory of Turin (Italy) andGeorge van Biesbroeck of theYerkes Observatory. The comet steadily faded after August, final (photographic) observations being obtained on 16 January 1940. The comet was also extensively observed from theIncheon Meteorological Observatory between July and September 1939.[5] W. H. Dirk captured a series of photographic plates of the comet alongside recording its positions from August to September 1939.[6]
Following the 1939 rediscovery, the comet's orbit was calculated byJens P. Möller (Copenhagen,Denmark), andKatherine P. Kaster andThomas Bartlett (Berkeley, USA).[7] Aperihelion date of 9 August 1939 was indicated. Based on these early orbits,Leland E. Cunningham of theHarvard College Observatory suggested that the comet was likely identical with Herschel's comet of 1788.
The final calculation of the orbit, byBrian G. Marsden in 1974, used 75 positions from both apparitions of the comet in 1788 and 1939–40 in addition to perturbations by planets, and linked the two sightings, with a perihelion date of 9 August 1939 and a period of 155 years.
| Numbered comets | ||
|---|---|---|
| Previous 34D/Gale | 35P/Herschel–Rigollet | Next 36P/Whipple |
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