THE ASTRONOMER Electronic Circular No 475 1991 Jan 10 20.25UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise, Basingstoke,
Hants, RG22 4PP, England. Telephone: (0256)471074 Int:+44256471074
Telex: 94082518 Answerback: TAGUY Microlink: MAG60138
JANET:GMH @ UK.AC.CAM.ASTRONOMY.STARLINK GUYH@UK.AC.SUSSEX.CLUSTER
TELECOM GOLD: 10074:MIK2885 PRESTEL 256471074
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PERIODIC COMET METCALF-BREWINGTON (1991a)
The following precise positions have been reported:
1991 UT R.A. (1950) Decl. m1 Observer
Jan. 7.44002 0 07 03.33 - 6 13 14.2 8.5 Ohtsuka
7.44341 0 07 03.80 - 6 13 11.1 "
8.47812 0 09 47.96 - 6 01 45.4 McNaught
9.45139 0 12 23.08 - 5 50 58.1 "
9.47448 0 12 26.65 - 5 50 43.8 "
T. Ohtsuka (YGCO Chiyoda Observatory). 300-mm telephoto lens.
Measurer T. Kojima. Communicated by S. Nakano.
R. H. McNaught (Siding Spring). Uppsala Southern Schmidt.
The central condensation brightens to a nearly-stellar point.
B. G. Marsden, Center for Astrophysics, notes that preliminary
orbital elements from the above observations strongly resemble
those of P/Metcalf (1906 VI). An unpublished prediction for
P/Metcalf made in 1975 by R. J. Buckley, Malvern, England, repre-
sents the above observations within 1 deg. Adjustment by Delta(T)
= -1.8 days reduces the residuals to 1'.
Rob McNaught, Australia e-mails:
"1991 Jan 08.486 UT Uppsala Southern Schmidt.
10 minute exposure on hypered 4415 Technical Pan.
Comet shows a diffuse 2' diameter coma with a very pronounced 1' dia
central condensation. A 1' length bright narrow tail lies in PA 70,
with a much fainter narrow tail to 1.0 degrees in the same PA.
The comet was slowly fading at discovery, according to the orbit, so
the circumstance of 3 discoveries in 8.5 hours clearly indicated an
outburst. This is also clear from the H(10) of around 5 to 6.
With this the 11th return since discovery, and with searches for the
comet in the first few returns, and in 1983, it is clear that the
comet is usually quiescent and rather faint. According to Carrusi et
al, during its next orbit it will have a close approach to Jupiter,
increasing the perihelion distance from 1.6 AU to 2.5 AU. Clearly
the discovery at this point was fortuitous. With the greater
perihelion distance and increasingly unreliable orbit, recovery would
have become rather difficult."
Brian Marsden supplies the following elements
T = 1991 Jan. 5.099 ET Peri. = 207.717
e = 0.59340 Node = 187.037 1950.0
q = 1.59376 AU Incl. = 13.046
a = 3.91975 AU n = 0.127004 P = 7.76 years
1991 ET R.A. (1950) Decl. Delta r m1
Jan. 4 23 57.99 - 6 49.8 1.547 1.594 8.5
9 0 11.19 - 5 56.0
14 0 24.51 - 4 59.1 1.617 1.596 8.6
19 0 37.95 - 3 59.5
24 0 51.46 - 2 57.7 1.691 1.606 8.7
29 1 05.03 - 1 54.4
Feb. 3 1 18.64 - 0 50.2 1.770 1.622 8.8
IAUC 5160 (Revised Copy)
Guy M Hurst