Electronic Telegram No. 2436 Central Bureau for Astronomical Telegrams INTERNATIONAL ASTRONOMICAL UNION CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University; 20 Oxford St.; Cambridge, MA 02138; U.S.A. e-mail: cbatiau@eps.harvard.edu (alternate cbat@iau.org) URL http://www.cbat.eps.harvard.edu/index.html Prepared using the Tamkin Foundation Computer Network SUPERNOVA 2010hi IN NGC 6621 Ron Arbour, South Wonston, Hants, U.K., reports his discovery of an apparent supernova (mag 18.0) on unfiltered CCD images taken on Sept. 1.893 (limiting mag 19.2) and 2.883 UT using a 0.4-m f/5 Newtonian reflector (+ Starlight Xpress camera) in the course of his supernova patrol. The new object is located at R.A. = 18h13m00s.76, Decl. = +68d21'53".4 (equinox 2000.0), which is 30" east and 4" north of the center of the galaxy NGC 6621. Nothing is visible at this position on Digitized Sky Survey plates from 1989 Sept. 1 (limiting blue mag 20.8) and 1993 Aug. 12 (limiting red mag 19.5). Arbour adds that four further confirming images were obtained by Tom Boles between Sept. 1.9400 and 1.9435. Following posting on the Central Bureau's unconfirmed-objects webpage, S. Nakano (Sumoto, Japan) forwards information from a pre- discovery unfiltered CCD image of 2010hi obtained by Koichi Itagaki (Teppo-cho, Yamagata, Japan) using a 0.60-m f/5.7 reflector, yielding position end figures 00s.66 +/- 0s.04, 53".0 +/- 0".1 and the following magnitudes: 2008 June 12.685, [19.5; Sept. 1.608, 18.7; 2.565, 18.5 (limiting mag 19.5). NOTE: These 'Central Bureau Electronic Telegrams' are sometimes superseded by text appearing later in the printed IAU Circulars. (C) Copyright 2010 CBAT 2010 September 3 (CBET 2436) Daniel W. E. Green