Electronic Telegram No. 3434 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 SUPERNOVA 2013aj IN NGC 5339 = PSN J13540068-0755438 Giancarlo Cortini, Predappio, Italy, reports his discovery of an apparent supernova (mag 14.7) on several unfiltered images (limiting mag about 19.5) taken on Mar. 3.141 UT with a 0.35-m f/5.5 Schmidt-Cassegrain reflector (+ SXVR-H9 CCD camera). The new object is located at R.A. = 13h54m00s.68, Decl. = -7d55'43".8 (equinox 2000.0), which is 6" east and 8" north of the center of NGC 5339. Nothing is visible at this positoin on red and blue Palomar Sky Survey plates (no dates or limiting magnitudes provided). The variable was designated PSN J13540068-0755438 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2013aj based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2013aj (unfiltered unless noted otherwise): 2012 May 17.90, [19.0 (Cortini); 2013 Mar. 3.141, 14.6 (J. Brimacombe, Cairns, Australia; remotely with a 51-cm RCOS telescope + STL11K camera + luminance filter at the New Mexico Skies observatory near Mayhill, NM, U.S.A.; position end figures 00s.66, 44".1; image posted at website URL http://www.flickr.com/photos/43846774@N02/8526265048/); 4.055, 14.5 (Federica Luppi and Luca Buzzi, Varese, Italy; 0.38-m f/6.8 reflector; position end figures 00s.63, 43".4; reference stars from CMC-14 catalogue; image posted at URL http://www.astrogeo.va.it/pub/TOCP/PSN_N5339.jpg). Jujia Zhang and Changjun Wang, Yunnan Astronomical Observatory (YNAO); and Xulin Zhao and Xiaofeng Wang, Tsinghua University, report on an optical spectrogram (range 350-870 nm) of PSN J13540068-0755438 = SN 2013aj that was obtained on Mar. 4.87 UT with the 2.4-m telescope (+ YFOSC) at the LiJiang Gaomeigu Station of the YNAO. The spectrum is consistent with a type-Ia supernova a few days before maximum light. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that 2013aj matches with SN 2002er at -5 days. A weak absorption feature, perhaps due to C II 658.0-nm, can be detected at around 632.0 nm. Adopting a recession velocity of 2736 km/s (Theureau et al. 1998, A.Ap. Suppl. 130, 333) for the host galaxy, NGC 5339, they measure the velocity of the Si II 635.5-nm absorption feature to be about 11400 km/s. Cosimo Inserra, Morgan Fraser, and Joe Polshaw, Queen's University, Belfast; Nic Walton and Nadia Blagorodnova, Institute of Astronomy, Cambridge; Matt Nichol, Queen's University, Belfast; S. Benetti and A. Pastorello, Istituto Nazionale di Astrofisica, Padova Astronomical Observatory; S. Valenti, Las Cumbres Observatory Global Telescope and University of California at Santa Barbara; S. Taubenberger, Max-Planck-Institut fuer Astrophysik, Garching; S. J. Smartt, K. Smith, and D. Young, Queen's University, Belfast; M. Sullivan, University of Southampton; and A. Gal-Yam and O. Yaron, Weizmann Institute for Science, on behalf of the PESSTO collaboration (www.pessto.org), report that they obtained a spectrum of PSN J13540068-0755438 = SN 2013aj on Mar. 3 using the European Southern Observatory's New Technology Telescope (+ EFOSC2 with Grism#13) at La Silla. The spectrum is consistent with a young type-Ia supernova in NGC 5339. An excellent match is obtained with several type-Ia supernovae about one week before B-band maximum light. The classification was made via GELATO (Harutyunyan et al. 2008, A.Ap. 488, 383) and SNID (Blondin and Tonry 2007, Ap.J. 666, 1024). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2013 CBAT 2013 March 7 (CBET 3434) Daniel W. E. Green