46P/Wirtanen (0046P)

Type: Periodic Perihelion date: 19 May 2024 Perihelion distance (q): 1.1 Aphelion distance (Q) : 5.1 Period (years): 5.4 Eccentricity (e): 0.66 Inclination (i): 11.7 JPL orbit diagram COBS lightcurve Atlas Carl A. Wirtanen (Lick Observatory, California, USA) discovered this comet on photographic plates exposed with the 20-inch f/7.4 Carnegie astrograph on 17 January 1948. The comet was described as diffuse, with a central condensation, and magnitude 16. The comet was then at its brightest as it was moving away from both the sun and Earth. Wirtanen recovered the comet on 8 September 1954. It reached a maximum magnitude of 18.5. The comet has been observed at every apparition except for 1980. With perihelion coming on 22 May 1980, the comet spent the period of 6 March to 1 October within 20° of the sun. During the beginning of March the comet would have been 2.44 AU from the sun, just a little closer than its record distance of 2.54 AU on 6 February 1974. Unfortunately it was then at a much closer solar elongation (22° compared to 109° in 1975). As a result of orbital changes in the 1970s and 80s (see below), the comet's best apparition came in 1991. Recovered on 8 July 1991, by T. Seki (Geisei, Japan), the comet's total magnitude was 17. The comet passed closest to Earth on 8 September (1.3501 AU), at which time observers were giving magnitude estimates near 10. Close approaches to planets: • 0.53 AU from Jupiter on 1912 December 31 (decreased perihelion distance from 1.63 AU to 1.43 AU, and decreased orbital period from 6.82 to 6.32 years) • 0.75 AU from Earth on 1914 November 3 • 0.66 AU from Earth on 1927 December 14 • 0.65 AU from Earth on 1947 December 4 (contributed to comet's discovery) • 0.66 AU from Earth on 1967 November 27 • 0.28 AU from Jupiter on 1972 April 10 (decreased perihelion distance from 1.61 AU to 1.26 AU, and decreased orbital period from 6.65 to 5.87 years) • 0.47 AU from Jupiter on 1984 February 26 (decreased perihelion distance from 1.26 AU to 1.08 AU, and decreased orbital period from 5.87 to 5.50 years) • 0.92 AU from Earth on 2008 February 17 • 0.08 AU from Earth on 2018 December 16 • 0.76 AU from Earth on 2029 October 10 • 0.56 AU from Jupiter on 2042 November 25 (will increase perihelion distance from 1.08 AU to 1.22 AU, and increase orbital period from 5.49 to 5.78 years) Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 17-Aug-18 16.95 0.08 13.9 1.1 11-Sep-18 15.75 0.05 12.7 1.0 18-Sep-18 15.45 0.03 12.1 1.7 02-Oct-18 14.74 0.00 11.5 2.7 12-Oct-18 14.31 0.01 10.8 3.8 09-Nov-18 12.74 0.04 9.7 7.1 10-Jan-19 12.65 0.01 7.6 4.3 02-Jun-19 18.85 0.12 16.0 0.4