Circular No. 6550

Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION

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COMET C/1997 C1 (GEHRELS)

Further precise CCD positions have been reported as follows:

1997 UT α_{2000} δ_{2000} m_{1} Observer
Feb. 2.15372 9^{h}11^{m}06.^{s}61 +12^{o}19′34′′.2 18.0 Offutt
2.19910 9 11 05.07 +12 19 41.5 18.1  _{”}
2.50728 9 10 54.60 +12 20 28.6 17.1 Abe
2.51690 9 10 54.20 +12 20 28.8  _{”}
2.60463 9 10 51.16 +12 20 41.3  Yan
2.61329 9 10 50.87 +12 20 43.4 17.8  _{”}
2.81785 9 10 44.12 +12 21 15.3 18.0 Tichá
2.82769 9 10 43.84 +12 21 16.5  _{”}
2.95108 9 10 39.47 +12 21 35.7 17.0 Laurie
3.00616 9 10 37.57 +12 21 44.7  _{”}
3.64445 9 10 16.05 +12 23 23.2 17.3 Asami
3.65579 9 10 15.59 +12 23 23.4  _{”}

W. Offutt (Cloudcroft). 0.6-m f/7 Ritchey-Chrétien. Near-stellar conden-

sation ∼ 6′′, no significant coma, tail discernible to ∼ 80′′ in p.a. 287^{o}. H. Abe (Yatsuka). 0.26-m f/6 reflector. Communicated by S. Nakano. H. J. Yan and Y. J. Chen (Xinglong). 0.60-m Schmidt. Measurer Chen. J. Tichá and M. Tichý (Kleť). 0.57-m f/5.2 reflector. Measurer Tichý. S. P. Laurie (Church Stretton). 0.25-m Schmidt-Cassegrain. A. Asami (Hadano). 0.2-m f/6 reflector. Communicated by S. Nakano.

The following very uncertain, parabolic orbital elements are from 20 observations Feb. 1–3. It seems likely that the comet is of short period.

T = 1998 Apr. 20.929 TT  ω = 31.^{o}014
Ω = 203.382 }2000.0
q = 2.17053 AU  i = 3.269
1997 TT α_{2000}  δ_{2000}  Δ  r  ϵ  β  m_{1}
Feb. 1 9^{h}11.^{m}75 +12^{o}16.^{′}7 4.128 5.109 174.^{o}2 1.^{o}1 17.2
6 9 08.93 +12 29.5 4.084 5.068 176.0 0.8 17.1
11 9 06.06 +12 42.8 4.048 5.028 171.9 1.6 17.0
16 9 03.20 +12 56.4 4.021 4.987 166.5 2.6 17.0
21 9 00.41 +13 09.9 4.000 4.946 160.9 3.7 17.0
26 8 57.73 +13 23.3 3.988 4.905 155.3 4.8 16.9
Mar. 3 8 55.22 +13 36.3 3.982 4.864 149.7 5.9 16.9
1997 February 3  \begin{matrix}c \\ ◯ \end{matrix} Copyright 1997 CBAT  Brian G. Marsden