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79P/du Toit–Hartley
Discovery
Discovered by	Daniel du Toit, Boyden Observatory, South Africa and Malcolm Hartley of the UK Schmidt Telescope Unit, Siding Spring, Australia
Discovery date	9 April 1945
Designations
Alternative designations	1987 IX, 1986q, 79P/1982 C1-A, 1982 II, 1982b, 79P/1945 G1, 1945 II, 1945c
Orbital characteristics
Epoch	9 December 2014
Aphelion	4.83 AU
Perihelion	1.1233 AU
Semi-major axis	2.9460 AU
Eccentricity	0.6187
Orbital period	5.06 a
Inclination	3.145°
Last perihelion	13 Sep 2018; 23 Aug 2013
Next perihelion	2023-Sep-30

79P/du Toit–Hartley or du Toit 2 is a periodic comet, now divided into two parts, in the Solar System with an orbital period of 5.06 years. It next comes to perihelion in September 2023 but is only expected to reach about apparent magnitude 18.^[3] It will be less than 90 degrees from the Sun from February 2023 until June 2024. On 26 May 2024 it will be 2.7 AU from the Sun and Earth.^[4]

It was originally discovered by Daniel du Toit at the Boyden Observatory, Bloemfontein, South Africa (then administered by Harvard College) on 9 April 1945 with a brightness of apparent magnitude 10.^[5]

Uncertainties in the calculation of the orbit meant the comet was lost until rediscovered by Malcolm Hartley of the UK Schmidt Telescope Unit, Siding Spring, Australia in 1982, when it was found to have broken into two parts, probably in 1976. Both parts had a brightness of magnitude 17. Observed in 1987, it was missed in 1992 but rediscovered by astronomers at Los Molinos Observatory, Uruguay on 4 March 2003 at magnitude 17. Fragment 79P-B is lost as it only has a 23-day observation arc from 1982.

References

^ MPC
^ "Horizons Batch for 79P-B/du Toit-Hartley (90000843) on 2023-Sep-30" (Perihelion occurs when rdot flips from negative to positive). JPL Horizons. Retrieved 2022-06-27. (JPL#17 Soln.date: 2021-May-04)
^ ^a ^b Seiichi Yoshida (2022-12-10). "79P/du Toit-Hartley". Seiichi Yoshida's Comet Catalog. Retrieved 2023-08-05.
^ "Horizons Batch for 79P-B/du Toit-Hartley (90000843) on 2024-May-26". JPL Horizons. Retrieved 2023-08-05. (JPL#17 Soln.date: 2021-May-04)
^ "79P/du Toit-Hartley". Cometography. Archived from the original on 5 July 2008. Retrieved 25 February 2015.