December 15, 2011: IAU CBAT Central Bureau Electronic Telegram 2943 (Daniel W. E. Green, Ed.) announces the discovery of an apparent supernova in NGC 4984 by Koichi Itagaki, Yamagata, Japan, at unfiltered CCD magnitude 12.7 on 2011 Dec. 9.856 UT.
Coordinates: R.A. = 13 08 58.39 Decl. = -15 31 04.1 (2000.0)
SN 2011iy is 16.6" east and 6.1" south of the nucleus of NGC 4984.
The variable was designated PSN J13085839-1531041 when it was posted on the Central Bureau's Transient Objects Confirmation Page webpage (http://www.cbat.eps.harvard.edu/unconf/tocp.html ).
Spectra by J. Chen and X.-F. Wang (Tsinghua Center for Astrophysics, Tsinghua University), X.-L. Wang, J.-J. Zhang, and J.-M. Bai (Yunnan Astronomical Observatory of China), and T.-M. Zhang (National Astronomical Observatories of China) obtained on 2011 Dec. 11.8 UT, and by M. Yamanaka and T. Ui (Hiroshima University) and A. Arai (Kyoto Sangyo University) obtained on Dec. 14.81 UT indicate SN 2011iy is a type-Ia discovered one to two weeks after maximum.
Itagaki's discovery image is posted at http://www.k-itagaki.jp/images/psn4984.jpg . An image by Joseph Brimacombe, Cairns, Australia, is posted at http://www.flickr.com/photos/43846774@N02/6492127541/ .
Additional observations reported to the AAVSO (all via CBET 2943): 2007 Feb. 25.708 UT, <19.5 (Itagaki); 2011 Dec. 10.541, 12.5 (Brimacombe, remotely using New Mexico Skies Observatory facilities near Mayhill, NM, position end figures 58.47s, 04.6"); 10.785, 12.8 (T. Noguchi, Katori, Chiba-ken, Japan, position end figures 58.38s, 04.2",via S. Nakano, Sumoto, Japan).
Observers are encouraged to monitor SN 2011iy (VSX J130858.3-153104) until it becomes contaminated by the bqckground light from the galaxy.
Charts for SN 2011iy (AUID 000-BKG-771) may be plotted using the AAVSO Variable Star Plotter (VSP): http://www.aavso.org/vsp 
Please report observations to the AAVSO International Database using the name SN 2011iy.
This AAVSO Special Notice was compiled by Elizabeth O. Waagen.
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