------------------------------------------------------------------- THE ASTRONOMER Electronic Circular No 3136 2016 Jan 15 11.04UT 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 P/2010 V1 = P/2015 Y2 (IKEYA-MURAKAMI) Z. Sekanina, Jet Propulsion Laboratory, reports tentative analysis of the offsets of nuclei A and B from January 1-4 suggests that they separated from the parent comet in the course of the 2010 return and quite possibly during the major outburst, which is estimated to have begun on 2010 Nov. 1, some 20 days after perihelion and shortly before the comet was discovered. The leading nucleus B is with near certainty the primary, more massive fragment, while nucleus A is its companion; this is plainly reflected in their times of perihelion passage, with nucleus B preceding by 0.017 day. The slightly greater brightness of A is apparently due to its current activity. Independent evidence comes from the different tail orientations. The tail of component B, in PA 290 deg, is directed along the projected orbit behind it (and towards component A) and is in fact a trail of coarse debris originating at the time of splitting. On the other hand, the tail of nucleus A, in PA about 240 deg, is closer to the anti-solar direction and contains recent ejecta. Once nucleus B grows more active, it should become as bright as A or even brighter. The analysis suggests a very low differential non-gravitational acceleration between both fragments and their separation with a submetre-per-second velocity. Both may survive the 2016 March perihelion and beyond. Predicted separations and position angles of nucleus A relative to B (0h UT): Jan. 13, 112", 294 deg; Jan. 23, 121", 293 deg; Feb. 2, 126", 291 deg; Feb. 12, 126", 289 deg; Feb. 22, 123", 288 deg. CBET 4235 Nick James, Chelmsford has reported imaging (C11 + CCD) on 2016 January 3, the two components A and B of this comet despite being magnitude 19 and probably the faintest he has ever recorded from his observing site. Date TT R. A. (2000) Decl. Delta r Elong. 2016 01 15 09 50 01.0 +32 58 11 0.7323 1.6577 149.7 2016 01 16 09 50 04.0 +32 59 16 0.7262 1.6547 150.5 2016 01 17 09 50 04.5 +33 00 12 0.7202 1.6518 151.2 2016 01 18 09 50 02.5 +33 00 59 0.7144 1.6490 152.0 2016 01 19 09 49 58.0 +33 01 36 0.7087 1.6462 152.7 2016 01 20 09 49 51.1 +33 02 02 0.7033 1.6435 153.5 2016 01 21 09 49 41.7 +33 02 17 0.6979 1.6408 154.2 2016 01 22 09 49 30.0 +33 02 19 0.6928 1.6381 154.9 2016 01 23 09 49 16.0 +33 02 08 0.6878 1.6355 155.6 2016 01 24 09 48 59.7 +33 01 43 0.6830 1.6329 156.3 2016 01 25 09 48 41.2 +33 01 03 0.6784 1.6304 157.0 2016 01 26 09 48 20.5 +33 00 08 0.6739 1.6280 157.6 2016 01 27 09 47 57.7 +32 58 56 0.6696 1.6255 158.2 2016 01 28 09 47 32.9 +32 57 27 0.6655 1.6232 158.8 2016 01 29 09 47 06.1 +32 55 41 0.6616 1.6209 159.4 2016 01 30 09 46 37.5 +32 53 35 0.6578 1.6186 159.9 Guy M Hurst