Electronic Telegram No. 2883 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 2011hd IN PGC 28823 = PSN J09584830+3447033 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; 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 unfiltered Catalina Sky Survey (CSS) images: SN 2011 UT R.A. (2000.0) Decl. Mag. Offset 2011hd Oct. 24.51 9 58 48.30 +34 47 03.3 15.9 6".8 E, 7".9 S The variable was designated PSN J09584830+3447033 when it was posted on the Central Bureau's TOCP webpage and is here designated SN 2011hd based on the spectroscopic confirmation reported below. Additional CCD magnitudes (unfiltered unless otherwise noted) for 2011hd: Apr. 29.26 UT, [20.5 (CSS); Oct. 25.463, 15.9 (J. Brimacombe, Cairns, Australia; position end figures 48s.33, 03".7); 28.425, 16.2 (R. A. Koff, Bennett, CO, USA, Meade 0.25-m f/10 reflector + Apogee AP-47p camera; position end figures 48s.31, 03".2; image scale 2"/pixel; limiting magnitude 19.0); 30.112, R = 16.0 (Federica Luppi, Varese, Italy, 0.36-m f/7.9 reflector + Bessell R filter; position end figures 48s.34, 03".5; reference stars from CMC-14 catalogue; image posted at URL http://www.astrogeo.va.it/pub/TOCP/PSN_09584830+3447033.jpg). Brimacombe's image is posted at URL http://www.flickr.com/photos/43846774@N02/6281645148/. G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group, reports that a spectrum (range 340-740 nm) of PSN J09584830+3447033 = 2011hd was obtained on Oct. 28 UT by P. Berlind with the F. L. Whipple Observatory 1.5-m telescope (+ FAST). Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows that 2011hd is a type-Ia supernova more than two weeks after maximum light. A good fit is found to the template of the normal type-Ia supernova 2003du at +18 days and z = 0.015. L. Tomasella, A. Pastorello, S. Valenti, and S. Benetti, Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Padova, on behalf of a larger collaboration, report that a spectrogram of 2011hd, obtained on Sept. 30.12 UT with the Ekar-Copernico 1.82-m telescope (+ AFOSC; range 360-810 nm; resolution 2.2 nm), is that of a type-Ia supernova. Comparison of the observed spectrum with a library of supernova spectra, using the "GELATO" code (Harutyunyan et al. 2008, A.Ap. 488, 383), suggests a normal type-Ia supernova 2-3 weeks after its B-band maximum brightness. The expansion velocity derived from the Si II 635.5-nm minimum is about 10000 km/s. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2011 CBAT 2011 November 1 (CBET 2883) Daniel W. E. Green