Electronic Telegram No. 2128 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 NOVA OPHIUCHI 2010 S. Nakano, Sumoto, Japan, reports the discovery by Hideo Nishimura (Miyawaki, Kakegawa, Shizuoka-ken, Japan) of a possible nova (mag 8.4) on two 13-s frames (limiting magnitude 11.0, measured by Nakano) taken on Jan. 15.857 UT with a Canon EOS 5D Digital Camera (+ Minolta 120-mm f/3.5 lens), providing the position as R.A. = 17h39m41s, Decl. = -21d39'47" (equinox 2000.0; measured by Nishimura). Nothing appears at this position on a frame from Jan. 13.86 (limiting mag about 9.5, assessed by Nishimura) or on frames taken monthly during 2009 Jan. 29-Nov. 3 (limiting mag 11.0). However, Nishimura did identify a faint image on a frame taken on Jan. 14.865, from which Nakano derives mag 10.1 (and limiting mag 10.6) and position end figures 41s.3, 54" for the new object; Nakano also measures mag 8.8 and position end figures 40s.90, 50".5 from Nishimura's discovery image on Jan. 15. Additional position end figures and magnitudes forwarded by Nakano for the presumed nova from unfiltered CCD frames taken by other observers: Jan. 16.856, 40s.94, 47".9, mag 8.4 (K. Itagaki, Takanezawa station, Tochigi-ken, Japan, 0.30-m f/7.8 reflector); Jan. 16.860, 40s.97, 47".4, mag 8.2 (K. Kadota, Ageo, Saitama-ken, Japan, 0.25-m f/5 reflector). Kadota adds that nothing is visible at this position on a red Digitized Sky Survey image from 1997 (limiting mag estimated to be 20 by Nakano). Itagaki has posted his image at website URL http://www.k-itagaki.jp/images/pn-sgr.jpg. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 January 16 (CBET 2128) Daniel W. E. Green