Electronic Telegram No. 1737 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://www.cfa.harvard.edu/iau/cbat.html SUPERNOVA 2009bt IN UGC 2542 G. Cortini, Predappio, Italy, reported his discovery of an apparent supernova (mag about 17.0) on unfiltered CCD images (limiting mag about 18.5) taken on Mar. 22.77 and 23.87 UT with a 35-cm telescope at the Monte Maggiore Observatory, giving the position of the new object as R.A. = 3h09m22s, Decl. = +70o33'36" (equinox 2000.0), but later (after the reports below were received) revising it to R.A. = 3h08m57s, Decl. = +70o33'36", noting it to be 26".6 east and 12".8 south of the center of the galaxy UGC 2542. Nothing is visible at this position on images taken by Cortini on 2008 Nov. 9.83 (limiting mag about 18.5) or on Palomar Sky Survey red and blue plates (no dates or limiting magnitudes provided). Following posting on the Central Bureau's unconfirmed-objects webpage, V.-P. Hentunen and M. Nissinen, Varkaus, Finland, report that they obtained images with a Celestron C-14 XLT telescope (+ Optec NextGen 0.5x focal reducer + SBIG ST 8 XME CCD camera) that show a new star of mag 16.9 on May 24.732 at R.A. = 3h08m57s.08, Decl. = +70o33'35".1, which is 10" east and 13" south of the center of UGC 2542; nothing is visible at this position on their 90-s image from Feb. 15.729 (limiting mag 20.0) or on the an F plate from the Palomar Sky Survey (limiting red mag 20.8). Also, C. Jacques and E. Pimentel, Belo Horizonte, Brazil, write that two stacked, unfiltered 300-s CCD images (limiting mag 19.0) taken remotely on Mar. 25.08 with a 25-cm f/3 reflector at Gras Observatory near Mayhill, NM, U.S.A., show a star of mag 16.6 at R.A. = 3h08m56s.98, Decl. = +70o33'35".3, adding that nothing is visible at this position on a Digitized Sky Survey image from 1992 Sept. 28 (limiting red mag 19.5). All these observers add that nothing is visible at the first position reported (see above) by Cortini. T. Puckett, Ellijay, GA, U.S.A., reports that a CCD image taken with a 40-cm reflector in Portal, AZ, in poor conditions on Mar. 25.140 yields position end figures 56s.99, 34".9. and mag 17.1 for 2009bt. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2009 CBAT 2009 March 25 (CBET 1737) Daniel W. E. Green