Electronic Telegram No. 2479 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 2010ik IN UGC 112 David Grennan, Raheny (Dublin), Ireland, reports his discovery of an apparent supernova (mag approximately 18.7 at discovery) on an unfiltered CCD image (limiting mag 19.5) taken on Sept. 17.9416 UT with a 0.36-m Schmidt- Cassegrain telescope. The new object is located at R.A. = 0h12m07s.48 +/- 0s.01, Decl. = +41d45'24".6 +/- 0".3 (equinox 2000.0), which is approximately 1".2 west and 10".6 north of the center of UGC 112. Nothing is visible at this position on Palomar Sky Survey red and blue plates (limiting mag 19.5). Additional magnitudes for 2010ik from Grennan: 2010 Aug. 20, [19.2; Sept. 20.887, 19.5 (limiting mag 20.4); 29.840, 18.7 (limiting mag 19.8). Ron Arbour (South Wonston, Hants, U.K., 0.40-m f/4 reflector) reports the following CCD magnitudes (unfiltered unless noted otherwise) for 2010ik: Sept. 18.829, 17.7 (poor conditions with clouds and bright moonlight; limiting mag about 18.1; position end figures 07s.45, 24s.8); 29.851, V = 18.5 (limiting mag 20.3; position end figures 07s.45, 24".7); Oct. 1.876, 18.1 (limiting mag 20.4; position end figures 07s.50, 24".5; offset 13".8 west, 10".9 north). Martin Mobberley, Suffolk, U.K., reports that 2010ik appeared at unfiltered CCD mag 18.5 on an image taken on Sept. 29.828 using a 0.43-m f/6.8 Cassegrain reflector located at Nerpio Observatory, Spain. T. Boles, Coddenham, England, reports mag 20.1 for 2010ik (and position end figures 07s.8, 24".3; offsets 10".7 west and 11".2 north; limiting mag 21.0) on Sept. 20. Boles' image has been posted at website URL http://www.supernova.myzen.co.uk/images/ugc112-marked.jpg. S. J. Smartt and S. Valenti, Queen's University, Belfast; S. Mattila, E. Kankare, S. Katajainen, and S. A. Bird, Tuorla Observatory; and T. Pursimo, Nordic Optical Telescope, report that they obtained low-resolution spectra (range 320-910 nm) of 2010ik on Oct. 3.95 UT with the Nordic Optical Telescope (+ ALFOSC). The spectrum suggests that 2010ik is a type-Ib/c supernova at approximately 1-2 weeks after maximum light; however, some peculiarities exist. Comparison of the spectrum of 2010ik with a library of supernova spectra using the "GELATO" code (Harutyunyan et al. 2008, A.Ap. 488, 383) yields a good match with the type-Ib/IIb supernova 2008bo (Navasardyan et al. 2008, CBET 1325) and with the peculiar type-Ib supernova 2005bf (Anupama et al. 2005, Ap.J. 631, 125), but with a redshift of z = 0.025, which is much higher than the redshift of the likely host, UGC 112 (z = 0.016, from NED). Fixing the redshift at z = 0.016, there is also a reasonable match with the spectrum of the type-IIb supernova 2008ax (Pastorello et al. 2008, MNRAS 389, 955) at seven days after maximum. The authors further report that an image from the NOT provided magnitude R about 18.7 for 2010ik on the same date (Oct. 3), and (assuming a Hubble Flow distance to UGC 112 of 70 Mpc) this suggests an absolute magnitude of -15.7 (after correction for foreground extinction of A_R about 0.19, from NED). If there is no further internal extinction from the host galaxy, this is faint for a type-Ib/c or type-IIb supernova. Furthermore, the measured magnitudes of Grennan, Boles, and Arbour suggest that 2010ik has had a "plateau-type" phase for around two weeks, which is again unusual for a type-Ib/c or type-IIb supernova. Further monitoring of this peculiar event is encouraged. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 October 5 (CBET 2479) Daniel W. E. Green