Taichi Kato, Franz-Josef Hambsch, Hiroyuki Maehara, Gianluca Masi, Ian Miller, Ryo Noguchi, Chihiro Akasaka, Tomoya Aoki, Hiroshi Kobayashi, Katsura Matsumoto, Shinichi Nakagawa, Takuma Nakazato, Takashi Nomoto, Kazuyuki Ogura, Rikako Ono, Keisuke Taniuchi, William Stein, Arne Henden, Enrique de Miguel, Seiichiro Kiyota, Pavol A. Dubovsky, Igor Kudzej, Kazuyoshi Imamura, Hidehiko Akazawa, Ryosuke Takagi, Yuya Wakabayashi, Minako Ogi, Kenji Tanabe, Joseph Ulowetz, Etienne Morelle, Roger D. Pickard, Tomohito Ohshima, Kiyoshi Kasai, Elena P. Pavlenko, Oksana I. Antonyuk, Aleksei V. Baklanov, Kirill Antonyuk, Denis Samsonov, Nikolaj Pit, Aleksei Sosnovskij, Colin Littlefield, Richard Sabo, Javier Ruiz, Thomas Krajci, Shawn Dvorak, Arto Oksanen, Kenji Hirosawa, William N. Goff, Berto Monard, Jeremy Shears, David Boyd, Irina B. Voloshina, Sergey Yu. Shugarov, Drahomir Chochol, Atsushi Miyashita, Jochen Pietz, Natalia Katysheva, Hiroshi Itoh, Greg Bolt, Maksim V. Andreev, Nikolai Parakhin, Viktor Malanushenko, Fabio Martinelli, Denis Denisenko, Chris Stockdale, Mike Simonsen, Paul. J. Tristram, Akihiko Fukui, Tamas Tordai, Robert Fidrich, Kevin B. Paxson, Koh-ichi Itagaki, Youichirou Nakashima, Seiichi Yoshida, Hideo Nishimura, Timur V. Kryachko, Andrey V. Samokhvalov, Stanislav A. Korotkiy, Boris L. Satovski, Rod Stubbings, Gary Poyner, Eddy Muyllaert, Vladimir Gerke, Walter MacDonald II, Michael Linnolt, Yutaka Maeda, Hubert Hautecler
Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we collected times of superhump maxima for 86 SU UMa-type dwarf novae mainly observed during the 2011-2012 season. We confirmed the general trends recorded in our previous studies. There are some systems showing positive period derivatives despite the long orbital periods. We observed the 2011 outburst of the WZ Sge-type dwarf nova BW Scl, and recorded an O-C diagram similar to those of previously known WZ Sge-type dwarf novae. The WZ Sge-type dwarf nova OT J184228.1+483742 showed an unusual pattern of double outbursts composed of an outburst with early superhumps and one with ordinary superhumps. We propose an interpretation that a very small growth rate of the 3:1 resonance due to an extremely low mass-ratio led to a quenching of the superoutburst before ordinary superhumps appeared. We systematically studied ER UMa-type dwarf novae and found that V1159 Ori showed positive superhumps similar to ER UMa in the 1990s. The recently recognized ER UMa-type object BK Lyn dominantly showed negative superhumps, and its behavior was very similar to the present-day state of ER UMa. The pattern of period variations in AM CVn-type objects were very similar to short-period hydrogen-rich SU UMa-type dwarf novae, making them as helium analogue of hydrogen-rich SU UMa-type dwarf novae. SBS 1108+574, a peculiar hydrogen-rich dwarf nova below the period minimum, showed a very similar pattern of period variations to those of short-period SU UMa-type dwarf novae. The mass-ratio derived from the detected orbital period suggests that this system contains a brown-dwarf secondary if the white dwarf has a mass typical to dwarf novae. CC Scl, MASTER OT J072948.66+593824.4 and OT J173516.9+154708 showed only low-amplitude superhumps with complex profiles. (abridged)
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http://arxiv.org/abs/1210.0678
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