Central Bureau Electronic Telegrams, 1286, 1 (2008/March-0)
Supernova 2008ax in NGC 4490.
Abstract (from CDS):
S. Nakano had sent an e-mail to the Central Bureau of an independent discovery of 2008ax (cf. CBETs 1280, 1285) by Koichi Itagaki (Teppo-cho, Yamagata, Japan), but that original e-mail was never received; subsequent e-mails give the information that follows. Itagaki's discovery was made on numerous unfiltered 20-s CCD frames (limiting mag 19.5) taken around Mar. 4.62 UT using a 0.60-m f/5.7 reflector, showing 2008ax at mag 16.1; additional images from Mar. 4.75 and 4.80 showed the variable to be about 0.1 mag brighter. (The announcement of 2008ax via CBET 1280 was issued around Mar. 4.81 UT.) Itagaki measured 2008ax to be located at R.A. = 12h30m40s.84 ± 0s.01, Decl. = +41o38'15".4 ± 0".1 (equinox 2000.0), which is 53" east and 24" south of the center of NGC 4490. Nothing is visible on Itagaki's earlier frames (the most recent being taken on 2007 Feb. 27, with limiting mag 19.0) or on the Digitized Sky Survey.