Electronic Telegram No. 3446 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 2013ar = PSN J08374502+4928322 Tianmeng Zhang and Xu Zhou, National Astronomical Observatories of China (NAOC); and Li Zhou, Xiaofeng Wang, Kaicheng Zhang, and Juncheng Chen, Tsinghua University (THU), report the discovery of an apparent supernova (mag 18.9) on unfiltered CCD images taken on Mar. 14.50 UT using the 0.6-m NAOC Schmidt telescope in the course of the THU-NAOC Transient Survey (TNTS). The new object is located at R.A. = 8h37m45s.02, Decl. = +49d28'32".2 (equinox 2000.0), which is 9" west and 8" south of the center of the presumed host galaxy (SDSS J083745.58+492840.2). Nothing is visible at this position on archival TNTS images obtained on Mar. 2 (limiting mag about 20.0) or on a Palomar Sky Survey image (no date, limiting magnitude, or bandpass provided) viewed via the Digitized Sky Survey. The TNTS images are posted at website URL http://www.thca.tsinghua.edu.cn/~wangxf/TNTS/PSNJ08374502+4928322.png. The variable was designated PSN J08374502+4928322 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2013ar based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2013ar (unfiltered unless noted otherwise): Mar. 19.227, 18.5 (Joseph Brimacombe, Cairns, Australia; remotely with a 51-cm RCOS telescope + luminance filter located at the New Mexico Skies observatory near Mayhill, NM, U.S.A.; position end figures 44s.99, 33".0; image posted at website URL http://www.flickr.com/photos/43846774@N02/8581029881/); 19.268, 18.2 (R. A. Koff, Bennett, CO, USA; 0.25-m f/10 reflector + Apogee U-47 camera; limiting magnitude 19.7; position end figures 44s.97, 32".8; UCAC3 reference stars); 22.122, 17.5 (Federica Luppi and Luca Buzzi, Varese, Italy; 0.38-m f/6.8 reflector; position end figures 45s.04, 33".2; reference stars from CMC-14 catalogue; image posted at the following website URL: http://www.astrogeo.va.it/pub/TOCP/PSN_J08374502+4928322.jpg). Jujia Zhang and Jianguo Wang, Yunnan Astronomical Observatory (YNAO); and Xulin Zhao and Xiaofeng Wang, Tsinghua University, report on an optical spectrogram (range 350-880 nm) of PSN J08374502+4928322 = SN 2013ar that was obtained on Mar. 17.60 UT with the 2.4-m telescope (+ YFOSC) at the LiJiang Gaomeigu Station of the YNAO. The spectrum is consistent with that of a type-Ia supernova at 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 2013ar matches with SN 2000dn at -4 days. Adopting a redshift of 0.052 for the host galaxy, SDSS J083745.58+492840.2 (from Sloan Digital Sky Survey Data Release 2), they measure the velocity of the Si II 635.5-nm absorption feature to be about 11200 km/s. L. Tomasella, A. Pastorello, S. Benetti, E. Cappellaro, P. Ochner, and M. Turatto, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica, report that optical spectroscopy (range 340-820 nm; resolution 1.3 nm), obtained on Mar. 15.93 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC), shows that PSN J08374502+4928322 = SN 2013ar is a type-Ia supernova at z around 0.06. The best match was found with various type-Ia supernovae -- and, in particular, with supernova 1992A (Kirshner et al. 1993, Ap.J. 415, 589) about one week before maximum light. The expansion velocity of the supernova ejecta, as measured from the position of the minimum of the Si II 635-nm line, is about 13600 km/s. The Asiago classification spectra are posted at website URL http://graspa.oapd.inaf.it; 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 25 (CBET 3446) Daniel W. E. Green