Electronic Telegram No. 2637 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network PSN J10523453+2256052 IN NGC 3437 S. Howerton, Arkansas City, KS, U.S.A.; A. J. Drake, S. G. Djorgovski, A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology; J. L. Prieto, Carnegie Observatories; M. Catelan, Pontificia Universidad Catolica de Chile; E. C. Beshore and S. M. Larson, Lunar and Planetary Laboratory, University of Arizona; and E. Christensen, Gemini Observatory, reported (on Jan. 12) the Catalina Real-time Transient Survey's discovery of an apparent supernova in public images from the Catalina Sky Survey (CSS). The object is located at R.A. = 10h52m34s.53, Decl. = +22d56'05".2 (equinox 2000.0), which is 16".9 west and 2".2 north of the center of NGC 3437 (which itself has redshift z = 0.0042). CSS unfiltered-CCD magnitudes for the new object, which was designated PSN J10523453+2256052 and posted on the Central Bureau's "Transient Objects Confirmation Page": 2010 Dec. 11.47 UT, [19.5; 2011 Jan. 3.45, 19.1; 10.41, 18.4 (discovery observation). The type-Ic supernova 2004bm had position end figures 35s.33, 05".5 (cf. IAUC 8335). J. Vinko, University of Szeged; J. C. Wheeler and E. Chatzopoulos, University of Texas; and G. H. Marion, Harvard-Smithsonian Center for Astrophysics and University of Texas, report that PSN J10523453+2256052 appears to be a "supernova impostor" similar to SN 2008S (Smith et al. 2009, Ap.J. 697, L49; Botticella et al. 2009, MNRAS 398, 1041). A spectrum obtained on 2011 Jan. 15.30 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph, range 420-1020 nm) by J. Caldwell shows prominent, narrow Balmer emission lines superimposed on a blue continuum. No other spectral features are detected. The absence of Na D absorption and the presence of the blue continuum argues against significant reddening. Unlike SN 2008S, the Ca II infrared triplet is not detected in PSN J10523453+2256052. The FWHM of H-alpha is about 1000 km/s. The redshift estimated from the emission peaks is z = 0.0047, in agreement with that of the host galaxy, NGC 3437. At the mean distance of 25 Mpc listed in NED, the absolute magnitude would be -13.6, which is consistent with the brightness of supernova impostors and much less bright than normal supernovae. S. Taubenberger, Max-Planck-Institut fuer Astrophysik; A. Pastorello, Queen's University; N. Elias-Rosa, Institute for Space Studies, Institut de Ciencies de l'Espai, IEEC, Consejo Superior de Investigaciones Cientificas; S. Benetti, Istituto Nazionale di Astrofisica (INAF), Padova; and F. Bufano, INAF, Catania, on behalf of a larger collaboration, report that a spectrogram (range 380-960 nm, resolution 1.2 nm) of PSN J10523453+2256052 was obtained with the 2.2-m telescope (+ CAFOS) of the Calar Alto Observatory on Jan. 17.1 UT. The spectrum shows a rather flat continuum with prominent and narrow (FWHM about 1200 km/s) hydrogen lines in emission; weak Fe II lines are also detected. The spectral characteristics and the faint absolute magnitude at discovery resemble those expected in the eruption of a luminous blue variable. A follow-up campaign for this transient is in progress. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 January 18 (CBET 2637) Daniel W. E. Green