Electronic Telegram No. 842 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 POSSIBLE RADIO SUPERNOVA IN NGC 3628 M. K. Argo, T. W. B. Muxlow, R. J. Beswick, and A. Pedlar, Jodrell Bank Observatory, UNiversity of Manchester, report the detection of a possible radio supernova in NGC 3628. The source was detected at position R.A. = 11h20m17s.018, Decl. = +13o35'19".96 (equinox 2000.0), with a peak flux density of 1.1 mJy (3 sigma = 0.25 mJy) in observations carried out at 4.994 GHz with MERLIN at an angular resolution of 0".081 by 0".055 (position angle 18 degrees) on 2006 Dec. 15 and 16. This position within about 2" of the galaxy's center, apparently slightly to the south, located in an optically obscured part of the galaxy that contains a number of radio-bright supernova remnants. This transient object was not present in similar images made with MERLIN on 2006 Apr. 13. Further observations made between 2007 Jan. 19 and 30 failed to detect any emission at this position to a 3-sigma limit of 0.19 mJy, implying that the source has faded rapidly. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2007 CBAT 2007 February 14 (CBET 842) Daniel W. E. Green