Electronic Telegram No. 830 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 2006tg-2006tz P. Challis and S. Blondin, Harvard-Smithsonian Center for Astrophysics; T. Matheson, National Optical Astronomy Observatory; R. Foley, University of California, Berkeley; S. Rodney, University of Hawaii; B. Leibundgut and J. Spyromilio, European Southern Observatory, on behalf of the ESSENCE project (cf. CBET 717, 772; IAUC 8427, 8464), report the discovery of 20 supernovae on multiple R- and I-band images taken at the Blanco 4-m telescope (+ MOSAIC II camera) during 2006 Dec. 13-23 by project members. Spectroscopic observations (range 380-890 nm) were obtained with the Keck I telescope (+ LRIS), the Keck II telescope (+ DEIMOS), the Very Large Telescope (+ FORS1), the Magellan Baade Telescope (+ IMACS), and the Gemini Observatory (+ GMOS). The table below includes the peak R magnitude (i.e., not necessarily at the listed date of discovery), the spectroscopic redshift, and the spectroscopic supernova type. Max. SN 2006 UT R.A. (2000.0) Decl. R z Type 2006tg Nov. 28 2 04 14.171 - 4 40 18.67 22.2 0.52 Ia 2006th Nov. 28 23 29 00.967 - 8 54 04.16 20.5 0.14 II 2006ti Nov. 28 23 29 13.128 - 8 47 58.14 20.8 0.23 II 2006tj Dec. 13 1 09 23.282 + 0 42 42.26 22.4 0.52 Ia 2006tk Dec. 15 1 07 52.642 + 0 27 55.30 21.3 0.32 Ia 2006tl Dec. 15 1 09 17.279 - 0 40 27.97 21.5 0.27 Ia 2006tm Dec. 15 1 09 17.296 + 0 09 11.31 21.2 0.23 Ia 2006tn Dec. 17 2 05 36.025 - 5 08 46.28 23.2 0.67 Ia 2006to Dec. 17 2 07 34.386 - 4 00 04.22 23.2 0.68 Ia 2006tp Dec. 17 2 09 14.042 - 4 37 12.18 23.4 0.72 Ia 2006tq Dec. 17 2 10 00.698 - 4 06 00.91 22.1 0.26 Ic 2006tr Dec. 17 2 28 29.535 - 7 53 28.51 23.2 0.58 Ia 2006ts Dec. 19 2 10 18.686 - 3 32 26.32 22.5 0.56 Ia 2006tt Dec. 19 2 10 47.926 - 4 24 56.92 23.4 0.63 Ia 2006tu Dec. 19 2 29 56.537 - 7 59 50.79 22.2 0.44 Ia 2006tv Dec. 19 2 35 34.225 - 8 34 22.03 23.5 0.76 Ia 2006tw Dec. 21 1 08 54.227 + 0 17 56.50 21.6 0.40 Ia 2006tx Dec. 21 1 10 26.783 - 0 34 07.49 22.6 0.50 Ia 2006ty Dec. 21 1 10 45.362 + 0 34 04.46 20.5 0.19 Ia 2006tz Dec. 21 2 10 27.034 - 4 17 08.23 22.9 0.39 II NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2007 CBAT 2007 February 3 (CBET 830) Daniel W. E. Green