2008CBET.1631....1Y

H. Yamaoka, Kyushu University, reports the discovery by K. Itagaki (Yamagata, Japan) of a previously unknown variable star on a wide-field survey CCD image taken on Dec. 16.420 UT with a 0.21-m f/3 reflector. Confirming CCD images taken on Dec. 16.424 with a 0.60-m f/5.7 reflector show the variable's magnitude to be about 15.4 and its position to be R.A. = 21h31m22.41s, Decl. = -0d39'36".8 (equinox 2000.0). The star was fainter than mag 17.5 on his survey image taken on 2007 Nov. 2.492, and fainter than mag 16.7 on 2008 Dec. 1.420. A faint blue star (magnitudes u = 21.6, g = 21.4, r = 21.4, i = 21.7, z = 21.2) in the Sloan Digital Sky Survey appears to be identical with Itagaki's variable. Yamaoka adds that photometry by Maehara (Kyoto University) and A. Miyashita (Tokyo) indicate a short-period (about-100-min) modulation (amplitude about 0.1 mag), which indicates that this variable is a SU UMa-type dwarf nova. Following posting on the Central Bureau's unconfirmed-objects webpage, R. A. Koff (Bennett, CO, U.S.A.) writes that his unfiltered CCD images yield position end figures 22s.41, 37s.0 (with a USNO-B1.0-catalogue star of mag about 21 at position end figures 22s.35, 36".9) and the following approximate magnitudes (averaged over about 1 hr) for the variable: Dec. 18.02, 14.2 (B-V approximately +0.01); 20.06, 14.1; 23.06, 14.6; 25.06, 14.8.