70P/Kojima (0070P)

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Type: Periodic Perihelion date: 3 November 2021 Perihelion distance (q): 2.0 Aphelion distance (Q) : 5.3 Period (years): 7.0 Eccentricity (e): 0.45 Inclination (i): 6.6 JPL orbit diagram COBS lightcurve Nobuhisa Kojima (Ishiki, Aichi) discovered this comet in Virgo on 27 December 1970. He confirmed the find on 29 December. On both occasions the comet's brightness was estimated as magnitude 14. Kojima also described the comet as diffuse, with a condensation. The first parabolic orbit was computed by K. Hurukawa and was first published on 6 January. It indicated the perihelion date was 1 November 1970. Following the accumulation of more precise positions, B. G. Marsden computed the first elliptical orbit which was published on 3 February. It indicated the perihelion date was 6 October 1970 and the orbital period was 6.09 years. Orbits computed after the comet had been observed at other apparitions indicated the perihelion date was 7 October and the period was 6.16 years. Observations following the comet's discovery indicated it brightened to about 13 during early January 1970 and then began fading. It was last detected on 27 June, at which time Elizabeth Roemer determined the nuclear magnitude as 19.0. The comet approached Jupiter following the 1970 apparition. The two bodies passed 0.158 AU from one another on 10 April 1973. This ultimately acted to increase the comet's perihelion distance from 1.63 AU to 2.40 AU and increase the orbital period from 6.16 years to 7.85 years. A prediction for the comet's 1978 apparition was published in the 1977 British Astronomical Association Handbook. It was considered uncertain by perhaps 2 days. H. Kosai and Hurukawa (Kiso Station) recovered this comet with the 105-cm Schmidt telescope on 9 December 1977. They estimated the magnitude as 18, and described the comet as diffuse, without condensation. Observers at Harvard College Observatory's Agassiz station confirmed the recovery on 10 December. Interestingly, the precise positions indicated the predicted perihelion date required a correction of only -0.18 day. C. Kowal (Hale Observatories) subsequently found images of this comet on plates exposed with the Palomar Schmidt on 8 and December . For the first night, Kowal estimated the magnitude as 19, and described the comet as a "somewhat diffuse" image. Towards the end of December, Tsutomu Seki (Kochi Observatory, Geisei Station) found prerecovery images on a plate exposed on 5 December. About the middle of 1978, observers at Harvard College Observatory's Agassiz Station found prediscovery images on plates exposed on 12 and 15 November. The comet never became brighter than magnitude 18 and was last detected on 13 March 1978. The comet was next seen in 1985/1986 and 1992/1994. It was recovered by Spacewatch at both apparitions and the recovery magnitude was 20 in 1985 and 22.1 in 1992. The comet did not become bright enough to become visible in amateur telescopes at either apparition. The comet approached Jupiter following the 1994 apparition. The two bodies passed 0.147 AU from one another on 22 December 1996. This ultimately acted to decrease the comet's perihelion distance from 2.40 AU to 1.97 AU and decrease the orbital period from 7.85 years to 6.99 years. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 02-Feb-15 16.89 0.08 15.2 0.2 10-Feb-15 16.82 0.04 16.1 0.3 17-Feb-15 16.84 0.05 14.9 0.3 01-Mar-15 16.60 0.03 15.5 0.4 10-Mar-15 16.67 0.03 15.7 0.2 17-Mar-15 16.60 0.03 15.0 0.5 08-Apr-15 17.05 0.06 15.5 0.2 24-Apr-15 17.64 0.05 15.8 0.2 22-May-15 18.15 0.06 17.4 0.2 30-Mar-22 15.6 0.8 08-Apr-22 17.4 0.4 23-Apr-22 17.9 0.4 30-Apr-22 17.4 0.4 02-May-22 17.6 0.4 21-May-22 18.5 0.4 31-May-22 18.8 0.4 17-Jun-22 18.3 0.4