------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 2875 2012 Dec 03 17.24UT Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke, Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074 INTERNET: GUY@TAHQ.DEMON.CO.UK Backup: gmh@wdcc1.bnsc.rl.ac.uk WORLD WIDE WEB http://www.theastronomer.org ------------------------------------------------------------------- COMET C/2012 V4 Rob Matson, Newport Coast, CA, U.S.A., reports on CBET 3320 that he found images of a possible comet in SWAN/SOHO spacecraft images taken in 2012 November 7-19: RA DEC 2012 11 07.5 19 59.4 -52 56 249 2012 11 10.5 19 45.2 -46 52 249 2012 11 11.5 19 41.3 -44 48 249 2012 11 13.5 19 35.2 -41 12 249 2012 11 19.5 19 23.7 -35 03 249 Matson computed parabolic orbital elements (T = 2012 Dec. 6, q = 0.75 AU, i = 161 deg) to seek confirmation. Terry Lovejoy, Australia obtained images through trees and in moonlight on Sept. 29.4 UT (astrometry tabulated below) with a 20-cm reflector that showed a well-condensed comet of diameter 2' and mag about 10. Robert McNaught also quickly obtained images with the 0.5-m Uppsala Schmidt telescope at Siding Spring, confirming the SWAN object to be a comet, noting a "spring-onion" appearance with a strongly condensed condensation and a coma of diameter 1'.0 and a 6' tail in p.a. 101 deg. 2012 UT R.A. (2000) Decl. Mag. Observer Nov. 29.39934 19 16 21.76 -29 16 55.3 11.5 Lovejoy 30.41944 19 15 26.33 -28 28 24.3 11.7 " 30.42108 19 15 26.18 -28 28 19.6 10.9 McNaught 30.43043 19 15 25.67 -28 27 52.9 10.9 " Maik Meyer, Germany, suggested that the orbital elements of comet C/2012 V4 are similar to those of D/Pons-Gambart (1827 M1). S. Nakano (Sumoto, Japan) then tried linking the orbit but could not find anything where the 1827 residuals are smaller than 0.5 deg; he suggests that if the identification is correct, the period could be 62.1 yr, adding that the comet would have passed 1.27 AU from Saturn on 1830 June 22 and 1.30 AU from Uranus on 1959 May 27. Gareth Williams, Minor Planet Center, writes that an orbit based on just the 2012 observations can have 1/a ranging from about 0.1 to 0, meaning that the period is essentially indeterminate. The solution presented below is based on the assumption that this is a return of D/1827 M1 (Pons-Gambart), a supposition based on the similarity of elements by Williams (and a suggestion made independently by M. Meyer), and that two returns were missed. The 1827 observations are known to be extremely noisy, and this orbit represents seven normal places to about 0.5 deg. The 2012 astrometry and an ephemeris appears on MPEC 2012-X02. Epoch = 2012 Dec. 19.0 TT T = 2012 Dec. 19.7659 TT Peri. = 20.5369 e = 0.948936 Node = 320.8075 2000.0 q = 0.801202 AU Incl. = 136.8482 a = 15.690006 AU n = 0.0158588 P = 62.149 years Ephemeris: Date TT R. A. (2000) Decl. Delta r Elong. m1 2012 12 01 19 14 55.9 -28 01 26 1.4079 0.8738 37.9 11.7 2012 12 02 19 14 03.6 -27 15 45 1.4258 0.8666 36.7 11.6 2012 12 03 19 13 12.4 -26 31 12 1.4435 0.8598 35.5 11.6 2012 12 09 19 08 21.0 -22 24 15 1.5425 0.8261 28.6 11.6 2012 12 17 19 02 15.4 -17 37 44 1.6509 0.8029 20.2 11.6 2013 01 01 18 51 22.7 -10 01 10 1.7607 0.8330 13.1 11.9 Guy M Hurst