Electronic Telegram No. 1644 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 POSSIBLE NEW CATACLYSMIC VARIABLE IN URSA MAJOR H. Yamaoka, Kyushu University, reports the discovery by K. Itagaki (Yamagata, Japan) of a previously unknown variable star on a wide-field survey CCD image taken on Jan. 2.727 UT with a 0.21-m f/3 reflector. Confirming CCD images taken on Jan. 2.749 with a 0.30-m f/7.8 reflector show the variable's magnitude to be about 14.9 and its position to be R.A. = 10h26m37s.04, Decl. = +47d54'26".3 (equinox 2000.0). The star was fainter than mag 16.5 on his survey image taken on 2008 Jan. 31.627. A faint blue star in the Sloan Digital Sky Survey (magnitudes u = 20.2, g = 20.1, r = 20.1, i = 20.2, z = 19.9), has a catalogued position that is identical with the reported object. The outburst amplitude and the color at its quiesient phase suggest that the variable is possibly a dwarf nova caught in outburst. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2009 CBAT 2009 January 3 (CBET 1644) Daniel W. E. Green