2008CBET.1427....1C

D. Chamarro, A. Uecker, F. Yuan, M. D. Sisson, C. Akerlof, and T. Mckay, University of Michigan; R. Quimby, California Institute of Technology; and J. C. Wheeler, University of Texas, on behalf of the ROTSE collaboration, report the discovery of an apparent supernova (mag about 17.4) in unfiltered CCD images taken on June 24.20 and 24.23 UT with the 0.45-m ROTSE-IIIb telescope at McDonald Observatory. SN 2008dx is located at R.A. = 13h00m14s.31, Decl. = +27o57'16".4 (equinox 2000.0; uncertainty < 1"), which is about 339" east and 94" south from the center of the Coma cluster and 44".6 west and 2".6 south from the center of the nearest galaxy seen in the Sloan Digital Sky Survey (2MASX J13001768+2757192). Nothing is visible at this position on an image taken on June 23.2 (limiting mag about 18.1). A ROTSE-III finding chart can be found at the following website URL: http://www.rotse.net/rsvp/j130014.3+275716/j130014.3+275716.jpg