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IAUC 7327: C/1997 K2; V1494 Aql

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                                                  Circular No. 7327
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)

COMET C/1997 K2
     T. Makinen, Finnish Meteorological Institute, Helsinki; and
J.-L. Bertaux, Service d'Aeronomie, Verrieres-le-Buisson, report
for the SWAN team the probable discovery of a comet from its
hydrogen Lyman-alpha emission appearing on full-sky images
(wavelength range 10-180 nm) taken from the SOHO spacecraft during
May-July 1997:

     1997 UT           R.A. (2000) Decl.
     May  20.884       0 51.1      -22 16

The resolution is 1 square degree.  Further positional and orbital
information is given on MPEC 1999-X07.  The discovery was made by
Makinen in the course of a complete survey of visible comets in the
SWAN images during Jan. 1996-June 1998.  The appearance was
comparable to that of comet C/1997 O1 (Tilbrook) in SWAN images
during 1997 June 17-Sept. 6, suggesting that m_1 was roughly 10-12.
Peak Lyman-alpha intensity values (in Rayleighs) for C/1997 K2 were:
June 5.0 UT, 10.4; 7.4, 12.9; 13.1, 12.3; 14.8, 14.7; 24.5, 17.9;
26.6, 17.9; 28.7, 17.4.  The object increased in extent from 2 deg
x 2 deg to 6 deg x 4 deg during this time.

     W. Liller, Vina del Mar, Chile, reports that a CCD spectrogram
obtained of V1494 Aql on Dec. 3.0346 UT with an objective prism
shows H-alpha in emission at a level 31 percent above the
neighboring continuum; H-beta is faintly visible.  A. Frasca and S.
Messina, Osservatorio Astrofisico di Catania, report Stromgren
photometry of V1494 Aql at Serra La Nave on Mount Etna with the
0.91-m telescope on Dec. 3.712 UT (over about 0.5 hr):  V = 4.025
+/- 0.037, b-y = +0.536 +/- 0.014, m_1 = 0.054 +/- 0.019, c_1 =
0.978 +/- 0.037.  Variations of about 0.06-0.08 mag were observed
in all filters.
     Visual magnitude estimates:  Dec. 3.702 UT, 4.1 (R. J. Bouma,
Groningen, The Netherlands); 4.378, 4.6 (S. Yoshida, Ibaraki,
Japan); 4.670, 4.7 (K. Sarneczky, Budapest, Hungary); 4.774, 5.2
(C. Vitorino, Cabo da Roca, Portugal); 4.776, 4.8 (A. Pereira, Cabo
da Roca, Portugal); 4.778, 5.0 (A. P. da Silva Correia and J.
Rodrigues Ribeiro, Esposende, Portugal); 4.850, 5.2 (Vitorino);
4.852, 5.1 (Pereira).

                      (C) Copyright 1999 CBAT
1999 December 4                (7327)            Daniel W. E. Green

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