Circular No. 7084

Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION

Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.

IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)

        URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304

Phone 617-495-7244/7440/7444 (for emergency use only)

COMET 1999 A1 A. C. Beresford, Myrtle Bank, South Australia, reports the visual dis-

covery of a comet by Justin Tilbrook. Available observations:

1999 UT  α_{2000}  δ_{2000}  m_{1} Observer
Jan. 12.486  23^{h}38.^{m}0  −28^{o}12′  10.5 Tilbrook
13.46014 23 39 05.^{s}62 −29 44 24′′.1  Garradd
13.46231 23 39 05.69 −29 44 34.2  _{”}
13.46432 23 39 05.84 −29 44 43.6  _{”}
13.46918 23 39 06.06 −29 45 07.5  _{”}
13.47238 23 39 06.23 −29 45 23.1  _{”}
13.47668 23 39 06.42 −29 45 43.4  _{”}
13.48825 23 39 07.03 −29 46 40.0 11.5  _{”}
13.49226 23 39 07.21 −29 46 59.6  Zoltowski
13.49604 23 39 07.43 −29 47 17.9  _{”}
13.50104 23 39 07.67 −29 47 42.7  _{”}

J. Tilbrook (Clare, South Australia). 0.2-m f/6 reflector, 70×. Hourly motion 120′′ southward. 40′′–50′′ coma, hint of nucleus, no tail. Jan. 13.49 UT: m_{1} = 10.2, 70′′–80′′ coma (0.15-m f/6 reflector).

G. J. Garradd (Loomberah). 0.45-m f/5.4 reflector + CCD. m_{2} = 16.7–

17.0. F. B. Zoltowski (Woomera). 0.30-m f/3.3 Schmidt-Cassegrain reflector +

CCD. Coma ∼ 1′ in diameter; signs of a faint, broad tail ∼ 3′ long in p.a. 80^{o}. m_{2} = 12.7.

COMET C/1998 P1 (WILLIAMS) Ephemeris extension to IAUC 7042 (orbital elements MPC 33189):

1999 TT α_{2000} δ_{2000} Δ r ϵ β m_{1}
Jan. 22 11^{h}44.^{m}86 +13^{o}23.^{′}0 1.072 1.860 129.^{o}5 24.^{o}1 10.3
Feb. 1 10 55.35 +24 13.9 1.049 1.971 151.4 13.8 10.6
11 9 57.35 +33 17.6 1.128 2.084 160.4  9.2 11.0
21 9 02.01 +38 45.5 1.297 2.197 147.6 14.0 11.5
Mar. 3 8 18.61 +41 12.4 1.531 2.311 131.6 18.7 12.1
13 7 48.87 +41 59.3 1.802 2.424 117.3 21.4 12.6
23 7 30.25 +42 01.8 2.093 2.537 104.8 22.3 13.1
Apr. 2 7 19.64 +41 47.7 2.393 2.650  93.6 22.1 13.6
12 7 14.58 +41 29.0 2.692 2.762  83.4 21.1 14.1
1999 January 13  \begin{matrix}c \\ ◯ \end{matrix} Copyright 1999 CBAT  Daniel W. E. Green