80P/Peters-Hartley (0080P)

Type: Periodic Perihelion date: 8 December 2022 Perihelion distance (q): 1.6 Aphelion distance (Q) : 6.4 Period (years): 8.1 Eccentricity (e): 0.60 Inclination (i): 29.3 JPL orbit diagram COBS lightcurve Christian Heinrich Friedrich Peters (Capodimonte Observatory, Naples, Italy) discovered this comet on 26 June 1846, in Libra. He described it as very faint, without a nucleus. He said it was very similar in appearance to a nebula situated a degree away, that was classified Herschel VI, no. 19. Peters confirmed his discovery on 27 and 28 June. Later orbits indicated the comet had already passed closest to the sun (3 June at 1.50 AU) and closest to Earth (4 June at 0.55 AU) before its discovery. The comet faded after discovery and was last detected on 21 July. During 1887, with the comet already having been missed at two probable returns, Berberich used 16 positions obtained during 1846, but no planetary perturbations, and determined the period as 13.38 years. He said the period was uncertain by about one year. Berberich added that this orbit indicated the comet made close approaches to Saturn in 1856 and 1883. Another investigation took place nearly a century later when Buckley examined the 1846 positions in 1976. He applied the perturbations by seven planets and concluded the orbital period had been 12.71 years; however, he still gave an uncertainty of about three years. Malcolm Hartley (U. K. Schmidt Telescope Unit, Australia) accidentally discovered this comet on a plate exposed on 11 July 1982 with the 1.2-m Schmidt telescope at Siding Spring. He estimated the brightness as magnitude 15 and said a faint halo was surrounding the comet's trailed image. Confirmation came on 13 July when the comet was photographed by observers at Perth Observatory. M. P. Candy (Perth, Australia) had already determined the comet was moving in an elliptical orbit by 19 July and suggested the comet was identical to the lost periodic comet Peters of 1846. Simultaneously it was announced that I. Hasegawa and S. Nakano came to similar conclusions. By 22 July the suggested link was apparently confirmed when B. G. Marsden noted that a revised orbit by Candy could be integrated backwards and arrive at a perihelion date only 10 days from that of comet Peters. He noted the orbital period was only 7.88 years in 1846. The comet was recovered at its next expected perihelion passage in 1990. R. H. McNaught (Siding Spring Observatory, Australia) found the comet with the Uppsala Southern Schmidt telescope on 26 May 1990. He described the comet as diffuse and magnitude 14. The precise positions indicated the prediction required a correction of +2.0 days. The comet continued to brighten and reached magnitude 13 during the last days of May and into June. It was last seen on 20 July at magnitude 16. The comet was next expected to arrive at perihelion on 11 August 1998 and was not expected to surpass magnitude 16 due to its unfavorable placement with respect to the Sun and Earth. It was recovered on 16 February 1998 and was only followed until 25 April. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' .