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IAUC 6859: 1998T; 69P

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IAUC number

                                                 Circular No. 6859
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)
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     H. Yamaoka, Kyushu University; T. Kato, Kyoto University; A.
V. Filippenko, University of California at Berkeley; and S. D. Van
Dyk, Infrared Processing and Analysis Center, California Institute
of Technology, report:  "The position of SN 1998T reported on IAUC
6844 is incorrect; the position derived from an R-band image taken
at the 0.95-m Ayabe Astronomical Observatory reflector on Mar. 18.5
UT (by M. Yamamoto) is R.A. = 11h28m33s.16, Decl. = +58o33'43".7
(equinox 2000.0; based on GSC positions).  Comparison with the
nearby star (R = 17.3, IAUC 6844) on the Ayabe image shows that SN
1998T was not brighter than R = 15.5, and was possibly at R > 16.0,
much dimmer than the reported visual magnitude estimates around
this epoch (see below).  This discrepancy could be due to
contamination by the host galaxy or to misidentification:  some
galaxy catalogues, including RC3, incorrectly identify IC 694; the
designation of Wynn-Williams et al. (see IAUC 6830) is also
incorrect, and it was the basis for originally assigning SN 1998T
to IC 694.  NGC 3690 (Markarian 171) is an interacting pair of
galaxies, and IC 694 is a small E/S0 galaxy located 1' northwest
of NGC 3690; these three compose Arp 299.  Note that NGC 3690
produced several supernovae in the past decade:  SN 1992bu (IAUC
5960), SN 1993G (IAUC 5718), and the probable radio supernova
reported on IAUC 4988.  Keck-2 spectra of the brightest knots,
obtained by Filippenko on Mar. 27, show that SN 1998T is the only
clear supernova in NGC 3690 at this time.  A chart of SN 1998T is
available at http://www.obs.misato.wakayama.jp/~ayabe/michi/ayabe.jpg."
     D. Balam reports that a check of his CCD image (cf. IAUC 6844)
shows no point source at the position specified above; he suggests
that SN 1998T may be hidden in the scatter caused by the galaxy
core on his frame.  K. Hornoch and M. Plsek, Lelekovice, Czech
Republic, reported on Mar. 28 that observations made on Mar. 26
show nothing at the correct position of SN 1998T down to visual
mag 16, and conclude that their earlier observations (cf. IAUC
6843, 6844) were not of SN 1998T and should therefore be

     Visual m_1 estimates:  Feb. 14.83 UT, 11.3 (A. Kammerer,
Ettlingen, Germany, 0.20-m reflector); Mar. 1.99, 11.9 (J. Warell,
Sandvreten, Sweden, 0.38-m refl.); 20.95, 11.8 (K. Sarneczky,
Agasvar, Hungary, 0.44-m refl.); 30.82, 12.3 (K. Hornoch,
Lelekovice, Czech Republic, 0.35-m reflector).

                      (C) Copyright 1998 CBAT
1998 April 3                   (6859)            Daniel W. E. Green

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