------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 1619 2001 Apr 01 13.50UT 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 GMH at AST.STAR.RL.AC.UK WORLD WIDE WEB http://www.demon.co.uk/astronomer ------------------------------------------------------------------- COMET C/2001 A2 (LINEAR) This object, initially thought to be asteroidal, was discovered by LINEAR as long ago as Jan.15 and posted on the NEO Confirmation Page. It was subsequently found to have a cometary appearance on CCD images taken by P. Pravec and L.Sarounova (Ondrejov; 0'.3 coma on Jan. 16.0 UT) and by M. Tichy and M. Kocer (Klet; diffuse, 10" coma on Jan. 16.9; m_1 = 17.2). A link was then found to an earlier image of 2001 January 3: 2001 UT R.A. (2000) Decl. m2 Jan. 3.31447 8 39 08.53 +14 20 48.8 19.0 Preliminary elements which appeared, along with discovery details, on IAUC 7564, indicated perihelion would be on 2001 May 24 with q=0.77977AU but the comet remaining faint and for this reason it was not announced on these e-circulars. Recently a further note on the Internet by M.Mattiazzo, Wallaroo, South Australia suggested that the total visual magnitude had brightened by about 2.5 magnitudes in the 24 hr ending Mar. 30.5UT, with the comet becoming noticeably more condensed in the same period. This has been followed by a substantial further surge in brightness increase: Visual m_1 estimates and coma diameters: Mar. 26.82, 10.8, 2'.5 (R. J. Bouma, The Netherlands, 0.25-m refl) 28.44, 10.7, 3'.5 (Mattiazzo, 0.20-m reflector); 29.94, 9.5, 3'.5 (A. Amorim, Brazil, 0.14-m reflector) 30.45, 8.6, 2'.9 (Y. Nagai, Yamanashi, Japan, 0.32-m refl) 30.52, 8.0, 3'.0 (Mattiazzo, S. Australia, 25x100B) 31.82, 7.5, 3' (Maciej Reszelski, Poland, 0.40-m refl.) Revised orbital elements: T 2001 May 24.5228 TT w 295.32570 ) e 0.99946100 O 295.12710 ) 2000.0 q 0.7790350 A.U. i 36.48320 ) Source: CBATComputer Positions are geocentric Ephemeris by Guy Hurst using EPH.EXE by Nick James: m = 13.0 + 5.0 log R + 10.0 log r Note: magnitudes based on original formula and disregard outburst: Date R.A. (2000) Dec. R r Elong Mag. Motion h m o ' (AU) (AU) o "/hr P.A. 2001 Apr 1.00 6 3.22 -6 44.1 0.938 1.260 81.0 13.9 46 208 2.00 6 2.66 -7 0.4 0.936 1.246 80.1 13.8 45 206 3.00 6 2.13 -7 16.7 0.934 1.233 79.1 13.8 45 205 4.00 6 1.64 -7 33.2 0.932 1.220 78.2 13.7 45 203 5.00 6 1.17 -7 49.8 0.930 1.206 77.3 13.7 45 202 6.00 6 0.73 -8 6.6 0.927 1.193 76.4 13.6 45 201 7.00 6 0.31 -8 23.5 0.924 1.180 75.5 13.5 45 199 8.00 5 59.92 -8 40.6 0.921 1.167 74.6 13.5 45 198 9.00 5 59.55 -8 57.9 0.918 1.154 73.8 13.4 45 197 10.00 5 59.20 -9 15.4 0.915 1.141 72.9 13.4 46 196 11.00 5 58.88 -9 33.1 0.911 1.129 72.1 13.3 46 195 12.00 5 58.56 -9 50.9 0.908 1.116 71.3 13.3 46 194 13.00 5 58.27 -10 9.0 0.904 1.103 70.5 13.2 47 193 14.00 5 57.99 -10 27.3 0.900 1.091 69.7 13.1 47 192 15.00 5 57.72 -10 45.8 0.896 1.078 68.9 13.1 48 192 Guy M Hurst