Electronic Telegram No. 1769

Central Bureau for Astronomical Telegrams
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://www.cfa.harvard.edu/iau/cbat.html

G. Pignata, J. Maza, M. Hamuy, R. Antezana, L. Gonzalez, P. Gonzalez, P. Lopez, S. Silva, G. Folatelli, D. Iturra, R. Cartier, F. Forster, S. Marchi, and A. Rojas, Universidad de Chile; B. Conuel, Wesleyan University; and D. Reichart, K. Ivarsen, A. Crain, D. Foster, M. Nysewander, and A. LaCluyze, University of North Carolina at Chapel Hill, on behalf of the CHASE project, report the discovery of an apparent supernova (mag approximately 18.2 +/- 0.4) on an unfiltered image taken on Apr. 15.13 UT with the 0.41-m 'PROMPT 4' telescope located at Cerro Tololo. The new object, which is also present in images taken on Apr. 3.32 (at mag approximately 18.8 +/- 0.5) and 17.08 (at mag approximately 18.1 +/- 0.4), is located at R.A. = 12h08m07s.21 +/- 0".1, Decl. = -31o59'25".3 +/- 0".1 (equinox 2000.0), which is about 1".6 west and 6".5 north of center of the presumed host galaxy. Nothing is visible at this position on archival images taken on Mar. 27.19 (limiting mag 19.2) and 30.31 (limiting mag 18.9) or on Digitized Sky Survey (limiting mag 19.0, though no passband or dates indicated).
J. Anderson and N. Morrell, on behalf of the Millenium Center for Supernova Science and the Carnegie Supernova Project collaboration, obtained spectroscopy (range 390-940 nm) of 2009dl and its host galaxy with the Magellan II Clay 6.5-m telescope (+ LDSS3) at Las Campanas Observatory on Apr. 17.2 UT. Inspection of the data reveals that 2009dl is a type-Ia supernova around maximum brigtness. From emission lines in the host-galaxy spectrum, they derive a redshift z = 0.1429 +/- 0.0001. Adopting that redshift, the Si II 635.5-nm absorption in the supernova spectrum is blueshifted by roughly 9000 km/s. Cross-correlation with a library of supernova spectra via the "Supernova Identification" tool (Blondin and Tonry 2007, Ap.J. 666, 1024) provides excellent matches with a variety of normal type-Ia supernovae, between 5 days before and 5 days after maximum light.

NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars.

2009 April 17
(C) Copyright 2009 CBAT
(CBET 1769)
Daniel W. E. Green