Electronic Telegram No. 2969 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 2011js IN NGC 1103 = PSN J02480496-1357511 S. Howerton, Arkansas City, KS, U.S.A.; A. J. Drake, S. G. Djorgovski, A. Mahabal, M. J. Graham, and R. Williams, California Institute of Technology; J. L. Prieto, Princeton University; M. Catelan, Pontificia Universidad Catolica de Chile; R. H. McNaught and G. Garradd, Australian National University; E. C. Beshore and S. M. Larson, Lunar and Planetary Laboratory, University of Arizona; and E. Christensen, Gemini Observatory, report the discovery of an apparent supernova in public images from the Catalina Sky Survey (CSS). SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011js Dec. 31.16 2 48 04.96 -13 57 51.1 17.7 15".2 W, 17".9 S The variable was designated PSN J02480496-1357511 when it was posted at the Central Bureau's TOCP webpage and is here designated SN 2011js based on the spectroscopic confirmation reported below. After posting on the TOCP, the following independent discovery report was received. J. Maza, M. Hamuy, R. Antezana, L. Gonzalez, R. Cartier, F. Forster, S. Silva, F. Carrasco, P. Sanchez, C. Hervias, and R. Ramirez, Universidad de Chile; G. Pignata, M. Cifuentes, Y. Apostolovski, and M. Vidal, Universidad Andres Bello; C. Farias and F. Aros, Pontificia Universidad Catolica de Chile; B. Conuel, Wesleyan University; G. Folatelli, IPMU, University of Tokyo; and D. Reichart, K. Ivarsen, J. Haislip, A. Crain, D. Foster, M. Nysewander, and A. LaCluyze, University of North Carolina at Chapel Hill, on behalf of the CHASE project (which is part of the Millennium Center for Supernova Science collaboration), report the discovery of an apparent supernova (mag approximately 17.1) on an unfiltered image taken on Dec. 31.10 UT with the 0.41-m 'PROMPT 4' telescope located at Cerro Tololo. The new object is located at R.A. = 2h48m05s.07 +/- 0".2, Decl. = -13o57'53".1 +/- 0".2 (equinox 2000.0), which is about 14".7 west and 22".1 south of the center of the galaxy NGC 1103. Additional CCD magnitudes for 2011js (unfiltered unless noted otherwise): 2011 Jan. 2.1-Nov. 19.1 UT, [20.5 (CHASE, thirteen stacked 80-s images); Oct. 30.25, [20.2 (CSS); Nov. 17.28, 19.4 (CSS); 29.11, [18.0 (CHASE); 2012 Jan. 1.059, 17.1 (Joseph Brimacombe, Cairns, Australia; remotely using a 51-cm RCOS telescope + STL11K camera + luminance filter at the New Mexico Skies Observatory near Mayhill, NM, U.S.A.; position end figures 05s.04, 53".0; image posted at URL http://www.flickr.com/photos/43846774@N02/6614195023/); 1.07, 16.3 (CHASE). J. M. Silverman and A. V. Filippenko, University of California, Berkeley, report that inspection of a CCD spectrum (range 340-1000 nm), obtained on Jan. 3 UT with the Shane 3-m reflector (+ Kast spectrograph) at Lick Observatory, shows that PSN J02480496-1357511 = SN 2011js is a young type-II supernova. The spectrum consists of a blue, nearly featureless continuum along with somewhat broad Balmer emission lines (FWHM about 2000 km/s for H-alpha; less for H-beta). There are also unresolved emission lines, probably from a superposed H II region having relatively low metallicity. M. Stritzinger, Oskar Klein Centre, Stockholm University; A. Pastorello, Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova; and G. Pignata, Universidad Andres Bello, on behalf of the Millennium Center for Supernova Science, report that they obtained a spectrum on Jan. 2.4 UT of PSN J02480496-1357511 = SN 2011js with the Gemini-South telescope (+ GMOS). The variable appears to be a type-IIn supernova near peak brightness. The spectrum exhibits a prevalent blue continuum with narrow emission features attributed to H_alpha, H_beta, and Na I D (the latter overimposed on a broad feature). Faint and narrow lines associated with Ca II (H & K) are discernible in absorption, while features related to the Ca II near-infrared triplet (including a very broad component) are tentatively identified. The overall appearance of this object is reminiscent of the early-epoch spectra of SN 1998S (Fassia et al. 2001, MNRAS 325, 907). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2012 CBAT 2012 January 7 (CBET 2969) Daniel W. E. Green