52P/Harrington-Abell (0052P)

Type: Periodic Perihelion date: 5 October 2021 Perihelion distance (q): 1.8 Aphelion distance (Q) : 5.9 Period (years): 7.6 Eccentricity (e): 0.54 Inclination (i): 10.2 JPL orbit diagram COBS lightcurve Robert G. Harrington and George O. Abell (Palomar Observatory, California, USA) discovered this comet on a plate taken on 22 March 1955, with the 122-cm Schmidt camera during the National Geographic Society-Palomar Sky Survey. The comet was estimated as magnitude 17, and was described as diffuse, with a central condensation, and a tail less than 1° long. The comet was confirmed on photographic plates exposed on 27 and 30 March. On the latter date, the nucleus was magnitude 19.0 and was surrounded by a faint coma. Leland E. Cunningham (Leuschner Observatory, Berkeley, California, USA) computed the first orbit which was published on 25 April 1955. It used the three initial Palomar positions and indicated the comet was moving in an elliptical orbit. The perihelion date was given as 18 December 1954, while the orbital period was 7.01 years. Because of the comet's faintness, it was not followed for a long time during its discovery apparition. George van Biesbroeck photographed it twice with the 82-inch reflector at McDonald Observatory during the latter half of April. He estimated the magnitude as 19.5 on each occasion, and said the coma was 5 arc seconds across. The comet was last seen on 18 May, when Elizabeth Roemer (Lick Observatory) obtained exposures of 120- and 100-minute durations, respectively, with the 36-inch f/5.8 Crossley reflector. She determined the magnitude as 19.2, and said the comet appeared slightly diffuse. The comet has been seen at every apparition, beginning with its first recovery on 26 January 1962 by Alan McClure. It tends to remain a faint object. Further appearances came in 1962, 1969, 1976, 1983, and 1991. K. Muraoka took positions from the years 1955-1990 and predicted the comet would next pass perihelion on 27 January 1999. The comet was recovered on 21 July 1998 by A. Maury (l'Observatoire de la Côte d'Azur, France). Using the 0.9-m Schmidt reflector and a CCD, he was expecting a comet faintly shining at a magnitude of 21 or 22, but instead detected a comet of magnitude 12.2. This unusual brightness was confirmed the next night by several observers who estimated the visual magnitude as 10.9 to 11.8. The coma was between 1 and 3 arc minutes across. The comet's enhanced brightness continued for many months and observers were reporting total magnitudes of about 11 around the time the comet passed perihelion on 27 January 1999. The coma diameter was then about 3 arc minutes across. The comet slowly faded during February and as March began most visual observers were estimating the magnitude as between 11.5 and 12. The coma was then slightly larger than 2 arc minutes. For most of first half of 1999, the comet continued to maintain its enhanced brightness for visual observers, although it finally dropped below magnitude 12 by the end of March, while the coma diameter had declined to 2 arc minutes. Observations continued throughout April and May. By the middle of the latter month, when previous brightness prediction formulas indicated the comet would be faintly shining at magnitude 19.5, most visual observers were still reporting the comet was between 12.7 and 13.0. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 04-Apr-14 16.88 0.04 15.9 0.2 12-Apr-14 17.05 0.13 16.3 0.2 15-Apr-14 16.95 0.10 15.8 0.2 21-Apr-14 16.81 0.07 15.9 0.2 03-May-14 17.43 0.04 15.6 0.2 27-May-14 17.89 0.14 16.7 0.2 08-Jun-14 18.05 0.16 17.4 0.2 10-Jun-14 18.12 0.12 17.8 0.2 18-Jun-14 18.36 0.11 18.1 0.2