Electronic Telegram No. 643 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://cfa-www.harvard.edu/iau/cbat.html SUPERNOVAE 2006fo, 2006gu-2006gx Further to CBETs 611 and 637, B. Bassett, South African Astronomical Observatory (SAAO); A. Becker, University of Washington (UW); H. Brewington, Apache Point Observatory (APO); C. Choi, Seoul National University (SNU); D. Cinabro, Wayne State University; F. DeJongh, Fermilab; J. Dembicky, APO; D. L. DePoy, Ohio State University (OSU); B. Dilday, University of Chicago (UC); M. Doi, University of Tokyo (UoT); J. Frieman, Fermilab and UC; P. Garnavich, University of Notre Dame; M. Harvanek, APO; C. Hogan, UW; J. Holtzman, New Mexico State University; M. Im, SNU; S. Jha, Stanford University (SU); K. Konishi, UoT; J. Krzesinski, APO; H. Lampeitl, Space Telescope Science Institute (STScI); R. Kessler, UC; B. Ketzeback, D. Long, O. Malanushenko, and V. Malanushenko, APO; J. Marriner, Fermilab; R. McMillan, APO; G. Miknaitis, Fermilab; T. Morokuma, UoT; R. Nichol, University of Portsmouth (UP); K. Pan, APO; J. L. Prieto, OSU; M. Richmond, Rochester Institute of Technology; A. Riess, STScI; R. Romani, SU; M. Sako, University of Pennsylvania; D. Schneider, Pennsylvania State University; M. Smith, UP; S. Snedden, APO; N. Takanashi and K. Tokita, UoT; K. van der Heyden, SAAO; S. Watters, APO; C. Wheeler, University of Texas; N. Yasuda, UoT; and C. Zheng, SU, on behalf of the Sloan Digital Sky Survey II collaboration, report the discovery of four new type-Ia supernovae on multiple g, r, and i images taken with the SDSS 2.5-m telescope at Apache Point Observatory by the SDSS observing team. Romani, Zheng, Sako, Wheeler, and Schneider, together with U. Hopp (University of Munich) and W. Kollatschny (University of Goettingen), report that spectroscopic observations with the Hobby Eberly Telescope on Sept. 20 and 21 UT show that the four new objects are all type-Ia supernovae. The discovery magnitudes tabulated below are all SDSS g magnitudes. Spectroscopic redshifts are given in the column labelled "z". Peak dates (all 2006) of expected maximum brightness are estimates from early fits to the multi-band light curves. SN Discov. R.A. (2000.0) Decl. Mag. z Estimated Date UT Peak Date 2006gu Aug. 27 0 40 38.96 - 0 04 24.9 21.1 0.24 Aug. 29 2006gv Sept.11 1 48 36.37 + 0 19 41.6 21.0 0.20 Sept.13 2006gw Sept.11 1 57 53.50 - 0 32 02.9 21.7 0.33 Sept.11 2006gx Sept.16 2 48 14.08 - 0 20 49.3 21.2 0.18 Sept.13 In addition, they report that further analysis of the NTT spectrum of 2006fo (Cf. CBET 624) shows it to be consistent with a type-Ic supernova, with features similar to that of 1999ex. NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2006 CBAT 2006 September 24 (CBET 643) Daniel W. E. Green