Electronic Telegram No. 1513 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A. IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions) CBAT@CFA.HARVARD.EDU (science) URL http://www.cfa.harvard.edu/iau/cbat.html SUPERNOVAE 2008fr AND 2008fs F. Yuan, University of Michigan; R. Quimby, California Institute of Technology; D. Chamarro and M. D. Sisson, University of Michigan; A. Uecker, Indiana University of Pennsylvania; C. Akerlof, University of Michigan; and J. C. Wheeler, University of Texas, on behalf of the ROTSE collaboration, report the discovery of two supernovae in unfiltered CCD images taken with the 0.45-m ROTSE-IIIb telescope at McDonald Observatory. Spectra (range 420-890 nm) of both objects were obtained with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by J. Caldwell and A. Westfall. SN 2008 UT R.A. (2000.0) Decl. Mag. Offset 2008fr Sep. 14.37 1 11 49.14 +14 38 27.0 17.3 -- 2008fs Sep. 21.28 1 09 05.75 +14 45 16.9 18.2 3".1 W, 3".9 S An extended object (magnitude r = 19.26) is seen at the position of 2008fr in a Sloan Digital Sky Survey (SDSS) image; a ROTSE finding chart for 2008fr is posted at http://www.rotse.net/rsvp/j011149.1+143827/j011149.1+143827.jpg. Spectra obtained on Sept. 22.26 UT were compared via SNID (Blondin and Tonry 2007, Ap.J. 666, 1024), showing 2008fr to be a type-Ia supernova around maximum light at z = 0.039 +/- 0.002; the minimum of the Si II 635.5-nm feature is blueshifted by 11000 km/s in the restframe. A ROTSE finding chart for 2008fs can be found at the following website URL: http://www.rotse.net/rsvp/j010905.8+144517/j010905.8+144517.jpg. Spectra obtained on Sept. 22.23 were compared via SNID, showing 2008fs's spectra to be best matched by that of SN 1999ex at nine days after maximum at z = 0.049 +/- 0.004. An average redshift of 0.044 +/- 0.005 was obtained from matching to type-Ib/c-supernovae spectra templates around ten days after maximum; this redshift is roughly consistent within uncertainty to that of the apparent SDSS host galaxy (z = 0.0386 +/- 0.0002, measured by SDSS). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2008 CBAT 2008 September 24 (CBET 1513) Daniel W. E. Green