Circular No. 4553 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. TWX 710-320-6842 ASTROGRAM CAM Telephone 617-495-7244/7440/7444 COMET HARTLEY (1988d) Malcolm Hartley reports his discovery of a comet on plates exposed with the U.K. Schmidt Telescope at Siding Spring. The object appears weak on the Feb. 19 I plate and exhibits an obvious 10' tail in p.a. 305 deg on the Feb. 22 J plate. Both images are near the edges of the plates. Measurements by R. H. McNaught: 1988 UT R. A. (1950) Decl. m1 Feb. 19.58883 10 12 16.57 - 3 00 46.4 16.5 19.65133 10 12 14.30 - 3 00 44.9 22.50434 10 09 52.49 - 2 56 20.5 22.57219 10 09 49.64 - 2 56 14.4 T PYXIDIS R. H. McNaught, Siding Spring Observatory, reports that his observations on Feb. 20.44, 21.49, and 22.60 UT, and observations by T. Cragg and RASNZ observers (reported via F. Bateson), show no change from the normal minimum magnitude of about 15 (cf. IAUC 4551). The star is marginally (0.1-0.2 mag) brighter than during 1985-86. PERIODIC COMET TEMPEL 2 (1987g) Z. Sekanina, Jet Propulsion Laboratory, California Institute of Technology, reports: "My recent determination of the rotation pole of P/Tempel 2 (Sekanina 1987, ESA SP-278, p. 323) indicates that the earth is currently located within 10 deg of the comet's equatorial plane and that this aspect will continue until early Aug. Comparison of this rotational model with photometric observations by Jewitt and Meech (1988, Ap.J., in press) in 1987 Mar.-Apr. suggests that the nucleus is strongly elongated perpendicular to its spin axis, implying a large rotation-induced brightness amplitude near the earth's transit across the equatorial plane. Attention is called to currently-favorable conditions (ephemeris on MPC 12329) for detecting large brightness variations due to nuclear rotation, although interference from occasional flare-ups is possible from 1987 Nov. on. These conditions should persist until the comet becomes too active for nucleus monitoring, probably in 1988 May-June. During another near-transit window, in 1989 Apr., the comet will be near conjunction with the sun." 1988 February 23 (4553) Daniel W. E. Green
Our Web policy. Index to the CBAT/MPC/ICQ pages.