Circular No. 6907

Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science) URL http://cfa-www.harvard.edu/iau/cbat.html Phone 617-495-7244/7440/7444 (for emergency use only)

SUPERNOVA 1998cc IN NGC 5172

W. D. Li, M. Modjaz, R. R. Treffers, and A. V. Filippenko, University of California at Berkeley, report their discovery of an apparent supernova (mag about 18.1) during the course of the Lick Observatory Supernova Search (cf. IAUC 6627) with the 0.8-m Katzman Automatic Imaging Telescope (KAIT). The object was found and confirmed on unfiltered CCD images obtained on May 15.3 and 16.3 UT, respectively. SN 1998cc is located at R.A. = 13h29m19s.31, Decl. = +17o02'42".4 (equinox 2000.0), which is about 24".5 due south of the nucleus of NGC 5172. No stars at the position of the supernova are visible in the Digital Sky Survey image of the field, while KAIT images obtained on Apr. 22 and 28 show a very faint source of roughly constant magnitude. Whether this faint source is an underlying H II region or the very early phase of the supernova remains to be determined by spectroscopic observations.

S. Jha, P. Garnavich, and R. Kirshner, Harvard-Smithsonian Center for Astrophysics, report that a spectrogram (range 350-760 nm) was taken of SN 1998cc by P. Berlind at the Whipple Observatory 1.5-m telescope (+ FAST spectrograph) on May 16.3 UT. The spectrum displays He I and strong Fe II absorption, indicating that the supernova is of type-Ib before maximum light. The host galaxy recession velocity, determined from narrow H-alpha emission, is 4080 km/s.

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Host galaxy info: V = 4030 km/s, 3.3'x1.7', SAB(s)bc:

SN type info: SN Ib

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