Electronic Telegram No. 3681 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 2013fw IN NGC 7042 = PSN J21134481+1334335 Zhangwei Jin, Ningbo, Zhejiang, China; and Xing Gao, Urumqi, Xinjiang, China, report the discovery of an apparent supernova (mag approximately 17.1) on two 40-s unfiltered CCD survey images (limiting mag about 19.0) taken by Gao in the course of the Xingming Sky Survey around Oct. 21.693 and 22.630 UT using a 35-cm f/6.9 Celestron C14 Schmidt-Cassegrain telescope at Mt. Nanshan. The new object is approximately located at R.A. = 21h13m44s.81, Decl. = +13d34'33".5 (equinox 2000.0), which is about 11".2 west and 3".5 north of the center of NGC 7042. Nothing is visible at this position on a Digitized Sky Survey image from 1991 Aug. 14 (limiting red mag about 19.8). The variable was designated PSN J21134481+1334335 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2013fw based on the spectroscopic confirmation reported below. Additional CCD magnitudes for 2013fw: 2013 Oct. 19, [19.2 (Jin and Gao); 23.244, 16.2 (R. A. Koff, Bennett, CO, USA; Meade 0.25-m f/10 reflector + Apogee U-47 camera; limiting mag 18.3; position end figures 44s.77, 33".1; UCAC3 reference stars; image posted at URL http://antelopehillsobservatory.org/SNpictures/PSNJ21134481+1334335final.jpg); 23.711, 16.5 (Gianluca Masi, Francesca Nocentini, and Patrick Schmeer, remotely using a 43-cm telescope at Ceccano, Italy; position end figures 44s.78, 33".1); 23.743, 16.6 (N. James, Chelmsford, Essex, England; Celestron C11 reflector; position end figures 44s.77, 33".3; image posted at website URL http://nickdjames.com/supernovae/2013/PSNJ21134481+1334335_20131023_ndj.jpg); 25.767, 16.2 (Masi et al.); 24.080, 16.6 (J. Brimacombe, Cairns, Australia; remotely with a 51-cm telescope located at the New Mexico Skies observatory near Mayhill, NM, U.S.A.; position end figures 44s.76, 33".6; image posted at website URL http://www.flickr.com/photos/43846774@N02/10485931233/). Masi et al. add that several low-resolution spectrograms of 2013fw were obtained on Oct. 25.74 remotely using a 36-cm telescope (+ 100 lines/mm grating, with a dispersion of 3.47 nm/pixel) at Ceccano, which show a clear Si II absorption around 615.0 nm, suggesting that 2013fw is a type-Ia supernova. D. A. Howell, Las Cumbres Observatory Global Telescope (LCOGT) and University of California at Santa Barbara (UCSB); D. Sand, Texas Tech University; and S. Valenti and I. Arcavi, LCOGT and UCSB, report that a spectrogram (wavelength range 320-1000 nm) of PSN J21134481+1334335 = SN 2013fw was obtained with the "Faulkes Telescope North" (+ FLOYDS) on Oct. 24.27 UT. The spectrum reveals 2013fw to be a type-Ia supernova with high- velocity features, observed well before maximum light. Adopting a redshift of z = 0.01695 for the host galaxy (NGC 7042), the Si 615.0-nm feature has a minimum at 18000 km/s, while the Ca infrared triplet has a minimum of approximately 28000 km/s. Using Superfit (Howell et al. 2005, Ap.J. 634, 1190), best fits are obtained to type-Ia supernovae at approximately two weeks before maximum light. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2013 CBAT 2013 October 30 (CBET 3681) Daniel W. E. Green