Electronic Telegram No. 3877 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 2014bc IN M106 = PSN J12185771+4718113 [Editor's note: this text replaces that on CBET 3876 (additional information and wavelength correction).] S. J. Smartt, K. W. Smith, D. Wright, D. R. Young, R. Kotak, M. Nicholl, J. Polshaw, C. Inserra, T.-W. Chen, G. Terreran, E. Gall, M. Fraser, and M. McCrum, Queen's University, Belfast; S. Valenti, Las Cumbres Observatory Global Telescope Network; R. Foley, University of Illinois; A. Lawrence, University of Edinburgh; S. Gezari, University of Maryland; W. Burgett, K. Chambers, M. Huber, R. P. Kudritzki, E. Magnier, J. Morgan, J. Tonry, W. Sweeney, R. Wainscoat, and C. Waters, University of Hawaii; C. Stubbs and R. Kirshner, Harvard University; N. Metcalfe and P. Draper, University of Durham; and A. Rest, Space Telescope Science Institute, report the discovery of a new transient source (magnitude z = 14.8) close to the core of M106 (NGC 4258) on images taken on May 19.25 UT with the 1.8-m Pan-STARRS1 telescope in the course of the PS1 NEO survey, with z-band reference frames from the PS1 Science Consortium 3Pi survey. The new object is located at R.A. = 12h18m57s.71, Decl. = +47d18'11".3 (equinox 2000.0), which is approximately 3".1 southeast of the center of the galaxy. No detection was made on the last Pan-STARRS1 image of this field on 2014 Mar. 24 (limiting r-band mag 20). The variable was designated PSN J12185771+4718113 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2014bc based on the spectroscopic confirmation reported below. Additional unfiltered CCD magnitudes for 2014bc: May 9.98 UT, 17.0: (Giancarlo Cortini, Predappio, Italy; 0.35-m f/5.5 Schmidt-Cassegrain reflector + SXVR H-9 camera; limiting mag 18.5; very faint; pre-discovery); 21.830 UT, 14.0 (Cortini); 21.888, 13.5 (Gianluca Masi, Francesca Nocentini, and Patrick Schmeer; remotely with a 43-cm telescope near Ceccano, Italy; position end figures 57s.69, 11".2; low-resolution spectra, obtained on May 21.90 with a 35.6-cm telescope at Ceccano with a grating having 100 lines/mm and dispersion 3.45 nm/pixel, shows H-alpha emission around 651 nm, suggesting a type-II supernova; image posted at website URL http://www.virtualtelescope.eu/?p=8059). P. Ochner, S. Benetti, L. Tomasella, A. Pastorello, N. Elias-Rosa, E. Cappellaro, and M. Turatto, Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica (INAF-OAPd); and and G. Terraran, INAF-OAPd and Queen's University, Belfast, report that a low-S/N optical spectrogram (range 335-785 nm; resolution 0.9 nm), obtained on May 21.82 UT with the Asiago 1.22-m Galileo Telescope (+ Boller & Chivens spectrograph) under the Asiago Transient Classification Program (Tomasella et al. 2014, as posted at website URL http://arxiv.org/abs/1403.7233), shows that PSN J12185771+4718113 = SN 2014bc is an evolved type-II supernova. The spectrum shows a red continuum having superimposed H-alpha and H-beta lines with P-Cyg profiles. From the shallow H-alpha absorption, and assuming a recession velocity of 448 km/s for the host galaxy, M106 (RC3; via NED), an expansion velocity of about 3700 km/s is deduced. A strong Na I D interstellar absorption suggests the presence of significant extinction. Superfit (Howell et al. 2005, Ap.J. 634, 1190) gives a good match with SN 1986I at 50 days after discovery (Pennypacker et al. 1989, A.J. 97, 186). The Asiago classification spectra are posted at website URL http://sngroup.oapd.inaf.it. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2014 CBAT 2014 May 22 (CBET 3877) Daniel W. E. Green