2009CBET.2107....1Z

W. Zheng and F. Yuan, University of Michigan; J. Vinko, University of Szeged; R. Quimby, California Institute of Technology; D. Chamarro, M. D. Sisson, N. Whallon, C. Akerlof, and S. B. Pandey, University of Michigan; and J. C. Wheeler and E. Chatzopoulos, University of Texas, on behalf of the ROTSE collaboration, report the discovery of two supernovae. SN 2009nn was discovered at mag about 17.3 in unfiltered images taken on Dec. 5.48 UT with the 0.45-m ROTSE-IIIb telescope at McDonald Observatory. SN 2009nn, whose magnitude remained at about 17.3 for the subsequent 23 days or so of monitoring, is located at R.A. = 12:33:56.42, Decl. = +13:55:09.0 (equinox 2000.0; uncertainty about 1"), which is 7".83 east and 0".65 north of the center of the host galaxy (SDSS J123355.87+135508.3). A finding chart for 2009nn can be found at the following website URL: http://www.rotse.net/rsvp/j123356.4+135509/j123356.4+135509.jpg. A spectrum of 2009nn, obtained on Dec. 23.45 with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by S. Rostopchin, shows it to be a type-IIn supernova with a smooth, blue continuum and prominent Balmer emission lines. No P-Cyg component is detected in any of the emission lines. The full-width of H-alpha at the continuum level is about 7000 km/s. The redshift, estimated from the narrow emission features, is 0.046, which agrees well with the SDSS "photo-z" value of 0.05 ± 0.01. SN 2009no was detected at mag about 17.3 in unfiltered images taken on Dec. 27.49 UT with the 0.45-m ROTSE-IIIb telescope, and again on Dec. 28.49 at mag about 17.4. SN 2009no is located at R.A. = 12:51:54.75, Decl. = +26:04:03.5 (equinox 2000.0; uncertainty about 1"), which is 4".04 east and 2".67 north of the center of the host galaxy (SDSS J125154.45+260400.8). A finding chart for the object can be found at the following website URL: http://www.rotse.net/rsvp/j125154.8+260404/j125154.8+260404.jpg. A spectrum, obtained on Dec. 30.40 as above by J. Caldwell, indicates that 2009no is a normal type-Ia supernova, a few days past maximum. The SuperNova IDentification code (SNID, Blondin and Tonry 2007, Ap.J. 666, 1024) finds that the best matching template is the spectrum of SN 1995D at five days after maximum. The expansion velocity, derived from the minimum of the Si II (rest 635.5 nm) line, is about 10000 km/s. A narrow H-alpha emission line is detected at 686.3 nm that is due to the imperfect subtraction of the host galaxy. The redshift (estimated from this narrow feature) is 0.0457, in perfect agreement with the spectroscopic redshift of the host (z = 0.0458) via the Sloan Digital Sky Survey.