97P/Metcalf-Brewington (0097P)


Type: Periodic Perihelion date: 15 February 2022 Perihelion distance (q): 2.6 Aphelion distance (Q) : 6.9 Period (years): 10.4 Eccentricity (e): 0.46 Inclination (i): 18.0 JPL orbit diagram COBS lightcurve The Reverend Joel Hastings Metcalf (Taunton, Massachusetts, USA) discovered this comet in Eridanus on a photograph exposed on 15 November 1906. He estimated the magnitude as 12, and described the comet as about 2 arc minutes across, with a distinct central condensation. The comet was extensively observed, but only until 16 January 1907. There was subsequently an uncertainty of several weeks in the orbital period and the comet was lost. Howard J. Brewington (near Cloudcroft, New Mexico, USA) was comet hunting on the night of 7 January 1991, when he found a diffuse object. He determined the total magnitude as 9.8 and said the object was strongly condensed. An independent discovery was made by William A. Bradfield on 7 January, but it was reported too late to rename the comet. On 9 January the Central Bureau for Astronomical Telegrams announced that Brewington's comet was identical to the lost periodic comet Metcalf. Computations revealed the comet would likely return to perihelion during June 1915. Searches were made and Leavitt reported she recovered this comet on 10 February 1915; however, a few days later, Edward Charles Pickering said the object found by Leavitt turned out to be a minor planet. The comet was not recovered, and in 1922 Gerald Merton revealed the comet had passed 0.86 AU from Jupiter on 15 September 1911, which slightly altered the orbit. For the 1922 apparition, searches were made using orbits supplied by A. C. D. Crommelin and Merton. The former astronomer suggested a perihelion date of 1921 December, while the second gave it as 3 March 1922. The comet was again not found. Searches were again attempted in 1929, using Merton's orbit which indicated a perihelion date of 23 November 1929. This was not considered a favorable apparition and the comet was not located. The comet was assumed lost and was generally ignored during the next 4 decades, but a new analysis of the 1906-1907 apparition was made by V. V. Emel'yanenko, N. Yu. Goryajnova, and N. A. Belyaev during 1975. They confirmed the close approach to Jupiter during September 1911, but added that additional close approaches occurred during August 1935 (1.17 AU) and August 1969 (1.05 AU). They predicted the comet would next arrive at perihelion on 20 June 1975, but searches revealed nothing. Another prediction was made for the comet's anticipated 1983 appearance. During early January Jeff Johnston and Michael Candy (Perth Observatory, Australia) were conducting a photographic search for the lost periodic comet when they found a 15th- magnitude diffuse object on a plate exposed on 5 January. Additional images were found on plates exposed on 7 and 9 January. The images did not represent the motion expected for comet Metcalf and the object was announced as a new comet. No further images were obtained and no reasonable orbit could be determined. Re- examination of the three plates revealed the "observations" were plate defects. Brewington found the comet just two days after its 5 January perihelion passage during 1991. The comet had actually passed closest to Earth on 16 September 1990 (1.0425 AU). After passing perihelion, the comet brightened to about magnitude 9 by mid-January, and then began fading. As the comet left the Sun's vicinity during 1991 it passed close to Jupiter on 28 March 1993 (0.11 AU). The result was the orbital period increasing to about 10.5 years and the perihelion distance increasing to about 2.61 AU. In the course of the routine search for near-Earth asteroids, LINEAR found an asteroid-like object on 1 September 2000. The magnitude was given as 19.0. G. V. Williams (Minor Planet Center) identified the "asteroid" as comet 97P. It was then 1.1° from the prediction, which indicated a correction to the predicted perihelion date of about +3.5 days. Observations (VEMag = visual equivalent magnitude) Date 10x10 mag Error VEmag Coma ' 01-Sep-21 20.0 0.4 15-Sep-21 18.9 0.4