Supernova 2011eb in NGC 782 = Psn J01573658-5748008
Abstract
L. A. G. Monard, Calitzdorp, Western Cape, South Africa, reports his discovery of an apparent supernova (mag 15.2) on several unfiltered CCD images taken on July 9.131 UT at the Klein Karoo Observatory. The new object is located at R.A. = 1h57m36s.58, Decl. = -57d48'00".8 (equinox 2000.0), which is 29" west and 34" south of the core of the SBb-type galaxy NGC 782. The variable was designated PSN J01573658-5748008 when posted on the Cenetral Bureau's TOCP webpage and is here designated SN 2011eb based on the spectroscopic reports below. Nothing is visible at this position on the Digitized Sky Survey (limiting red mag 20.5). Additional magnitudes for 2011eb: May 29.147, [18.7 (Monard); July 9.771, 16.3 (Joseph Brimacombe, Cairns, Australia; red filter; position end figures 36s.65, 47'59".3); 10.125, 15.3 (Monard); 11.804, 15.1 (Brimacombe; red filter). One of Brimacombe's images from July 9 is posted at the following website URL: http://www.flickr.com/photos/43846774@N02/5920090860/, while his image from July 11 is posted at http://www.flickr.com/photos/43846774@N02/5930061424/. D. Milisavljevic and R. Fesen, Dartmouth College; K. Nordsieck, University of Wisconsin; and T. Pickering and D. O'Donoghue, South African Astronomical Observatory, on behalf of a larger SALT Commissioning Team, report that low-dispersion spectra (range 320-890 nm), obtained on July 10.1 UT with the 10-m SALT telescope (+ RSS), show PSN J01573658-5748008 = SN 2011eb to be a type-Ia supernova. Cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) shows matches with normal type-Ia events around maximum light. After correcting for the recession velocity 6098 km/s (Wong et al. 2006, MNRAS 371, 1855; via NED) of its host galaxy NGC 782, the velocity of the Si II 635.5-nm feature is estimated to be approximately 11000 km/s. J. Parrent, Dartmouth College and Las Cumbres Observatory; with D. A. Howell, R. C. Thomas, P. E. Nugent, and M. Sullivan, write that a CCD spectrum (range 350-900 nm) of PSN J01573658-5748008 = SN 2011eb was taken with the Gemini South telescope on July 13 UT, indicating that this object is a type-Ia supernova within a few days of maximum light, based on comparisons to other spectra using "Superfit" (Howell et al. 2005, Ap.J. 634, 1190); the Doppler velocity of the Si II 635.5-nm absorption feature is about 11300 km/s, assuming a host-galaxy redshift of z = 0.02.
- Publication:
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Central Bureau Electronic Telegrams
- Pub Date:
- July 2011
- Bibcode:
- 2011CBET.2764....1M