Electronic Telegram No. 30 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html 2003gm IN NGC 5334 F. Patat, European Southern Observatory; and A. Pastorello, INAF-Padova, on behalf of the European Supernova Collaboration, report that J. Aceituno obtained two spectra (ranges 400-500 and 600-700 nm; resolutions 0.17 and 0.2 nm, respectively) with the Calar Alto 3.5-m telescope (+ TWIN spectrograph) on July 16.87 UT of the object given the supernova designation 2003gm (cf. IAUC 8164). The spectra show a featureless continuum, on which three emission lines -- identified as H_alpha, H_beta, and H_gamma from the Balmer series -- are visible, each showing a narrow peak overimposed on a broader component; the expansion velocities, deduced from the H_alpha profile, are 300 km/s and 1400 km/s (FWHM), respectively. The line peaks are redshifted at 1420 km/s, a value very similar to the host-galaxy recession velocity (1382 km/s, via NED). Even though the overall characteristics are similar to those of a type-IIn supernova, the distance to NGC 5334 (19.2 Mpc, assuming H_o = 72 km/s/Mpc) and the observed luminosity (IAUC 8164) imply that the absolute magnitude is about -14.4 -- i.e., quite low. This, together with the spectral appearance, seems to indicate that the object is not a real supernova, but rather an eta-Car-like event, similar to SN 1997bs (Van Dyk et al., 2000, 112, 1532). NOTE: These 'Central Bureau Electronic Telegrams' are intended to be preliminary announcements of items that later appear in the formal IAU Circulars. Citations should normally be made to IAUCs rather than to CBETs. (C) Copyright 2003 CBAT 2003 July 19 (CBET 30) Daniel W. E. Green