Circular No. 5911

Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION

Postal Address: Central Bureau for Astronomical Telegrams Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. Telephone 617-495-7244/7440/7444 (for emergency use only) TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505 MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)

COMET McNAUGHT-RUSSELL (1993v) R. H. McNaught provides remeasurements of the discovery R plate

taken by K. S. Russell (IAUC 5910) and also astrometry obtained by Mc-Naught and G. J. Garradd with the 0.61-m reflector at Siding Spring:

1993 UT α_{2000} δ_{2000} m_{1} Observer
Dec. 17.46003 3^{h}06^{m}33.^{s}61 −56^{o}33′25′′.7 17.5 Russell
17.50865 3 06 28.78 −56 33 25.1  _{”}
18.57315 3 04 46.10 −56 32 34.2  McNaught
18.59508 3 04 43.97 −56 32 32.5  _{”}
18.59767 3 04 43.69 −56 32 32.2  _{”}
18.60024 3 04 43.69 −56 32 32.2  _{”}
19.58014 3 03 11.00 −56 31 12.9  _{”}
19.58390 3 03 10.68 −56 31 12.7  _{”}

Preliminary parabolic orbital elements by B. G. Marsden, Harvard-Smithsonian Center for Astrophysics, from the above observations:

T = 1994 Apr. 1.357 TT  ω = 353.^{o}565
Ω = 166.772 }2000.0
q = 0.86594 AU  i = 52.027
1993/94 α_{2000}  δ_{2000}  Δ  r  ϵ  β  m_{1}
Dec. 19 3^{h}04.^{m}10 −56^{o}32.^{′}0 1.609 1.928 92.^{o}9 30.^{o}6 17.4
24 2 56.64 −56 19.0 1.575 1.863 90.4 31.9 17.2
29 2 50.16 −55 53.3 1.539 1.798 88.0 33.1 17.0
Jan. 3 2 44.84 −55 15.7 1.502 1.732 85.7 34.5 16.8
8 2 40.80 −54 27.1 1.463 1.667 83.4 35.9 16.5
13 2 38.14 −53 28.0 1.421 1.602 81.3 37.4 16.3
18 2 36.90 −52 19.0 1.377 1.537 79.3 39.0 16.1
23 2 37.07 −51 00.3 1.329 1.472 77.5 40.7 15.8
28 2 38.62 −49 31.7 1.278 1.408 75.8 42.7 15.5

3C 279 A. W. Neely, Silver City, NM, reports a flare of this BL Lac object, as

indicated by the following Johnson V magnitudes: Nov. 20 UT, 16.3 ± 0.3; Dec. 10, 14.8 ± 0.5; 18, 15.04 ± 0.1.

1993 December 20 Daniel W. E. Green