# William Stein

## Contact Details

NameWilliam Stein |
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## Pubs By Year |
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## Pub CategoriesSolar and Stellar Astrophysics (22) Mathematics - Number Theory (9) High Energy Astrophysical Phenomena (3) Mathematics - Algebraic Geometry (2) Computer Science - Computers and Society (1) Mathematics - History and Overview (1) Mathematics - Numerical Analysis (1) |

## Publications Authored By William Stein

**Authors:**Kosuke Namekata, Keisuke Isogai, Taichi Kato, Colin Littlefield, Katsura Matsumoto, Naoto Kojiguchi, Yuki Sugiura, Yusuke Uto, Daiki Fukushima, Taiki Tatsumi, Eiji Yamada, Taku Kamibetsunawa, Enrique de Miguel, William L. Stein, Richard Sabo, Maksim V. Andreev, Etienne Morelle, E. P. Pavlenko, Julia V. Babina, Alex V. Baklanov, Kirill A. Antonyuk, Okasana I. Antonyuk, Aleksei A. Sosnovskij, Sergey Yu. Shugarov, Polina Yu. Golysheva, Natalia G. Gladilina, Ian Miller, Vitaly V. Neustroev, Vahram Chavushyan, Jose R. Valdes, George Sjoberg, Yutaka Maeda, Hiroshi Itoh, Gianluca Masi, Raul Michel, Pavol A. Dubovsky, Seiichiro Kiyota, Tamas Tordai, Arto Oksanen, Javier Ruiz, Daisaku Nogami

We report on a superoutburst of a WZ Sge-type dwarf nova (DN), ASASSN-15po. The light curve showed the main superoutburst and multiple rebrightenings. In this outburst, we observed early superhumps and growing (stage A) superhumps with periods of 0. Read More

**Authors:**Colin Littlefield, Peter Garnavich, Mark R. Kennedy, Erin Aadland, Donald M. Terndrup, Grace V. Calhoun, Paul Callanan, Lyu Abe, Philippe Bendjoya, Jean-Pierre Rivet, David Vernet, Maxime Devogele, Benjamin Shappee, Thomas Holoien, Teofilo Arranz Heras, Michel Bonnardeau, Michael Cook, Daniel Coulter, Andre Debackere, Shawn Dvorak, James R. Foster, William Goff, Franz-Josef Hambsch, Barbara Harris, Gordon Myers, Peter Nelson, Velimir Popov, Rob Solomon, William L. Stein, Geoff Stone, Brad Vietje

**Category:**Solar and Stellar Astrophysics

In 2016 May, the intermediate polar FO~Aqr was detected in a low state for the first time in its observational history. We report time-resolved photometry of the system during its initial recovery from this faint state. Our data, which includes high-speed photometry with cadences of just 2 sec, shows the existence of very strong periodicities at 22. Read More

**Authors:**Mariko Kimura, Keisuke Isogai, Taichi Kato, Yoshihiro Ueda, Satoshi Nakahira, Megumi Shidatsu, Teruaki Enoto, Takafumi Hori, Daisaku Nogami, Colin Littlefield, Ryoko Ishioka, Ying-Tung Chen, Sun-Kun King, Chih-Yi Wen, Shiang-Yu Wang, Matthew J. Lehner, Megan E. Schwamb, Jen-Hung Wang, Zhi-Wei Zhang, Charles Alcock, Tim Axelrod, Federica B. Bianco, Yong-Ik Byun, Wen-Ping Chen, Kem H. Cook, Dae-Won Kim, Typhoon Lee, Stuart L. Marshall, Elena P. Pavlenko, Oksana I. Antonyuk, Kirill A. Antonyuk, Nikolai V. Pit, Aleksei A. Sosnovskij, Julia V. Babina, Aleksei V. Baklanov, Alexei S. Pozanenko, Elena D. Mazaeva, Sergei E. Schmalz, Inna V. Reva, Sergei P. Belan, Raguli Ya. Inasaridze, Namkhai Tungalag, Alina A. Volnova, Igor E. Molotov, Enrique de Miguel, Kiyoshi Kasai, William Stein, Pavol A. Dubovsky, Seiichiro Kiyota, Ian Miller, Michael Richmond, William Goff, Maksim V. Andreev, Hiromitsu Takahashi, Naoto Kojiguchi, Yuki Sugiura, Nao Takeda, Eiji Yamada, Katsura Matsumoto, Nick James, Roger D. Pickard, Tamás Tordai, Yutaka Maeda, Javier Ruiz, Atsushi Miyashita, Lewis M. Cook, Akira Imada, Makoto Uemura

**Category:**High Energy Astrophysical Phenomena

How black holes accrete surrounding matter is a fundamental, yet unsolved question in astrophysics. It is generally believed that matter is absorbed into black holes via accretion disks, the state of which depends primarily on the mass-accretion rate. When this rate approaches the critical rate (the Eddington limit), thermal instability is supposed to occur in the inner disc, causing repetitive patterns of large-amplitude X-ray variability (oscillations) on timescales of minutes to hours. Read More

**Authors:**Taichi Kato

^{1}, Franz-Josef Hambsch, Berto Monard, Tonny Vanmunster, Yutaka Maeda, Ian Miller, Hiroshi Itoh, Seiichiro Kiyota, Keisuke Isogai, Mariko Kimura, Akira Imada, Tamas Tordai, Hidehiko Akazawa, Kenji Tanabe, Noritoshi Otani, Minako Ogi, Kazuko Ando, Naoki Takigawa, Pavol A. Dubovsky, Igor Kudzej, Sergey Yu. Shugarov, Natalia Katysheva, Polina Golysheva, Natalia Gladilina, Drahomir Chochol, Peter Starr, Kiyoshi Kasai, Roger D. Pickard, Enrique de Miguel, Naoto Kojiguchi, Yuki Sugiura, Daiki Fukushima, Eiji Yamada, Yusuke Uto, Taku Kamibetsunawa, Taiki Tatsumi, Nao Takeda, Katsura Matsumoto, Lewis M. Cook, Elena P. Pavlenko, Julia V. Babina, Nikolaj V. Pit, Oksana I. Antonyuk, Kirill A. Antonyuk, Aleksei A. Sosnovskij, Aleksei V. Baklanov, Stella Kafka, William Stein, Irina B. Voloshina, Javier Ruiz, Richard Sabo, Shawn Dvorak, Geoff Stone, Maksim V. Andreev, Sergey V. Antipin, Alexandra M. Zubareva, Anna M. Zaostrojnykh, Michael Richmond, Jeremy Shears, Franky Dubois, Ludwig Logie, Steve Rau, Siegfried Vanaverbeke, Andrei Simon, Arto Oksanen, William N. Goff, Greg Bolt, Bartomiej Debski, Christopher S. Kochanek, Benjamin Shappee, Krzysztof Z. Stanek, Jose L. Prieto, Rod Stubbings, Eddy Muyllaert, Mitsutaka Hiraga, Tsuneo Horie, Patrick Schmeer, Kenji Hirosawa

**Affiliations:**

^{1}Kyoto U

**Category:**Solar and Stellar Astrophysics

Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we collected times of superhump maxima for 128 SU UMa-type dwarf novae observed mainly during the 2015-2016 season and characterized these objects. Read More

We describe the role the open-source software community plays in fixing bugs through a case study of a problem with integer determinant computations in SageMath. Read More

**Authors:**Mariko Kimura, Keisuke Isogai, Taichi Kato, Akira Imada, Naoto Kojiguchi, Yuki Sugiura, Daiki Fukushima, Nao Takeda, Katsura Matsumoto, Shawn Dvorak, Tonny Vanmunster, Pavol A. Dubovsky, Igor Kudzej, Ian Miller, Elena P. Pavlenko, Julia V. Babina, Oksana I. Antonyuk, Aleksei V. Baklanov, William L. Stein, Maksim V. Andreev, Tamás Tordai, Hiroshi Itoh, Roger D. Pickard, Daisaku Nogami

**Category:**Solar and Stellar Astrophysics

We present optical photometry of a WZ Sge-type dwarf nova (DN), ASASSN-15jd. Its light curve showed a small dip in the middle of the superoutburst in 2015 for the first time among WZ Sge-type DNe. The unusual light curve implies a delay in the growth of the 3:1 resonance tidal instability. Read More

**Authors:**Taichi Kato

^{1}, Enrique de Miguel, William Stein, Yutaka Maeda, Colin Littlefield, Seiichiro Kiyota, Tonny Vanmunster, Shawn Dvorak, Sergey Yu. Shugarov, Eugenia S. Kalinicheva, Roger D. Pickard, Kiyoshi Kasai, Lewis M. Cook, Hiroshi Itoh, Eddy Muyllaert

**Affiliations:**

^{1}Kyoto U

**Category:**Solar and Stellar Astrophysics

We observed the first-ever recorded outburst of PM J03338+3320, the cataclysmic variable selected by proper-motion survey. The outburst was composed of a precursor and the main superoutburst. The precursor outburst occurred at least 5 d before the maximum of the main superoutburst. Read More

Most systematic tables of data associated to ranks of elliptic curves order the curves by conductor. Recent developments, led by work of Bhargava-Shankar studying the average sizes of $n$-Selmer groups, have given new upper bounds on the average algebraic rank in families of elliptic curves over $\mathbb{Q}$ ordered by height. We describe databases of elliptic curves over $\mathbb{Q}$ ordered by height in which we compute ranks and $2$-Selmer group sizes, the distributions of which may also be compared to these theoretical results. Read More

**Authors:**Taichi Kato, Franz-Josef Hambsch, Pavol A. Dubovsky, Igor Kudzej, Berto Monard, Ian Miller, Hiroshi Itoh, Seiichiro Kiyota, Kazunari Masumoto, Daiki Fukushima, Hiroki Kinoshita, Kazuki Maeda, Jyunya Mikami, Risa Matsuda, Naoto Kojiguchi, Miho Kawabata, Megumi Takenaka, Katsura Matsumoto, Enrique de Miguel, Yutaka Maeda, Tomohito Ohshima, Keisuke Isogai, Roger D. Pickard, Arne Henden, Stella Kafka, Hidehiko Akazawa, Noritoshi Otani, Sakiko Ishibashi, Minako Ogi, Kenji Tanabe, Kazuyoshi Imamura, William Stein, Kiyoshi Kasai, Tonny Vanmunster, Peter Starr, Elena P. Pavlenko, Oksana I. Antonyuk, Kirill A. Antonyuk, Aleksei A. Sosnovskij, Nikolaj V. Pit, Julia V. Babina, Aleksandr Sklyanov, Rudolf Novak, Arto Oksanen, Shawn Dvorak, Raul Michel, Gianluca Masi, Colin Littlefield, Joseph Ulowetz, Sergey Yu. Shugarov, Polina Yu. Golysheva, Drahomir Chochol, Viktoriia Krushevska, Javier Ruiz, Tamas Tordai, Etienne Morelle, Richard Sabo, Hiroyuki Maehara, Michael Richmond, Natalia Katysheva, Kenji Hirosawa, William N. Goff, Franky Dubois, Ludwig Logie, Steve Rau, Irina B. Voloshina, Maksim V. Andreev, Kazuhiko Shiokawa, Vitaly V. Neustroev, George Sjoberg, Sergey Zharikov, Nick James, Greg Bolt, Tim Crawford, Denis Buczynski, Lewis M. Cook, Christopher S. Kochanek, Benjamin Shappee, Krzysztof Z. Stanek, Jose L. Prieto, Denis Denisenko, Hideo Nishimura, Masaru Mukai, Shizuo Kaneko, Seiji Ueda, Rod Stubbings, Masayuki Moriyama, Patrick Schmeer, Eddy Muyllaert, Jeremy Shears, Robert J. Modic, Kevin B. Paxson

**Category:**Solar and Stellar Astrophysics

Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we collected times of superhump maxima for 102 SU UMa-type dwarf novae observed mainly during the 2014-2015 season and characterized these objects. Read More

We present the 13-year light curve of HW Boo between 2001 May and 2014 May. We identified 12 outbursts, which typically lasted 2 to 5 days, with an amplitude of 2.7 to 3. Read More

**Authors:**Chikako Nakata, Taichi Kato, Daisaku Nogami, Elena Pavlenko, Tomohito Ohshima, Enrique de Miguel, William Stein, Kazuhiko Siokawa, Etienne Morelle, Hiroshi Itoh, Pavol A. Dubovsky, Igor Kudzej, Hiroyuki Maehara, Arne Henden, William N. Goff, Shawn Dvorak, Oksana Antonyuk, Eddy Muyllaert

**Category:**Solar and Stellar Astrophysics

We report on photometric observations of two dwarf novae, OT J075418.7+381225 and OT J230425.8+062546, which underwent superoutburst in 2013 (OT J075418) and in 2011 (OT J230425). Read More

**Authors:**Taichi Kato

^{1}, Tomohito Ohshima

^{2}, Denis Denisenko, Pavol A. Dubovsky, Igor Kudzej, William Stein, Enrique de Miguel, Arne Henden, Ian Miller, Kirill Antonyuk, Oksana Antonyuk, Nikolaj Pit, Aleksei Sosnovskij, Alex Baklanov, Julia Babina, Elena P. Pavlenko, Kazunari Matsumoto, Daiki Fukushima, Megumi Takenaka, Miho Kawabata, Daisuke Daisuke, Kazuki Maeda, Risa Matsuda, Katsura Matsumoto, Colin Littlefield, Arto Oksanen, Hiroshi Itoh, Gianluca Masi, Francesca Nocentini, Patrick Schmeer, Roger D. Pickard, Seiichiro Kiyota, Shawn Dvorak, Joseph Ulowetz, Yutaka Maeda, Raul Michel, Sergey Yu. Shugarov, Drahomir Chochol, Rudolf Novak

**Affiliations:**

^{1}Kyoto U,

^{2}Kyoto U

**Category:**Solar and Stellar Astrophysics

We report on a superoutburst of the AM CVn-type object SDSS J090221.35+381941.9 [J0902; orbital period 0. Read More

**Authors:**Taichi Kato

^{1}, Pavol A. Dubovsky, Igor Kudzej, Franz-Josef Hambsch, Ian Miller, Tomohito Ohshima, Chikako Nakata, Miho Kawabata, Hirochika Nishino, Kazunari Masumoto, Sahori Mizoguchi, Masayuki Yamanaka, Katsura Matsumoto, Daisuke Sakai, Daiki Fukushima, Minami Matsuura, Genki Bouno, Megumi Takenaka, Shinichi Nakagawa, Ryo Noguchi, Eriko Iino, Roger D. Pickard, Yutaka Maeda, Arne Henden, Kiyoshi Kasai, Seiichiro Kiyota, Hidehiko Akazawa, Kazuyoshi Imamura, Enrique de Miguel, Hiroyuki Maehara, Berto Monard, Elena P. Pavlenko, Kirill Antonyuk, Nikolaj Pit, Oksana I. Antonyuk, Aleksei V. Baklanov, Javier Ruiz, Michael Richmond, Arto Oksanen, Caisey Harlingten, Sergey Yu. Shugarov, Drahomir Chochol, Gianluca Masi, Francesca Nocentini, Patrick Schmeer, Greg Bolt, Peter Nelson, Joseph Ulowetz, Richard Sabo, William N. Goff, William Stein, Raul Michel, Shawn Dvorak, Irina B. Voloshina, Vladimir Metlov, Natalia Katysheva, Vitaly V. Neustroev, George Sjoberg, Colin Littlefield, Bartlomiej Debski, Paulina Sowicka, Marcin Klimaszewski, Malgorzata Curylo, Etienne Morelle, Ivan A. Curtis, Hidetoshi Iwamatsu, Neil D. Butterworth, Maksim V. Andreev, Nikolai Parakhin, Aleksandr Sklyanov, Kazuhiko Shiokawa, Rudolf Novak, Tat'yana R. Irsmambetova, Hiroshi Itoh, Yoshiharu Ito, Kenji Hirosawa, Denis Denisenko, Christopher S. Kochanek, Benjamin Shappee, Krzysztof Z. Stanek, Jose L. Prieto, Koh-ichi Itagaki, Rod Stubbings, Jose Ripero, Eddy Muyllaert, Gary Poyner

**Affiliations:**

^{1}Kyoto U

**Category:**Solar and Stellar Astrophysics

Continuing the project described by Kato et al. (2009, PASJ, 61, S395, arXiv:0905.1757), we collected times of superhump maxima for 56 SU UMa-type dwarf novae mainly observed during the 2013-2014 season and characterized these objects. Read More

**Authors:**Tomohito Ohshima, Taichi Kato, Elena Pavlenko, Hidehiko Akazawa, Kazuyoshi Imamura, Kenji Tanabe, Enrique de Miguel, William Stein, Hiroshi Itoh, Franz-Josef Hambsch, Pavol A. Dubovsky, Igor Kudzej, Thomas Krajci, Alex Baklanov, Denis Samsonov, Oksana Antonyuk, Viktor Malanushenko, Maksim Andreev, Ryo Noguchi, Kazuyuki Ogura, Takashi Nomoto, Rikako Ono, Shin'ichi Nakagawa, Keisuke Taniuchi, Tomoya Aoki, Miho Kawabata, Hitoshi Kimura, Kazunari Masumoto, Hiroshi Kobayashi, Katsura Matsumoto, Kazuhiko Shiokawa, Sergey Yu. Shugarov, Natalia Katysheva, Irina Voloshina, Polina Zemko, Kiyoshi Kasai, Javier Ruiz, Hiroyuki Maehara, Natalia Virnina, Jani Virtanen, Ian Miller, Boyd Boitnott, Colin Littlefield, Nick James, Tamas Tordai, Fidrich Robaert, Stefono Padovan, Atsushi Miyashita

We carried out the photometric observations of the SU UMa-type dwarf nova ER UMa during 2011 and 2012, which showed the existence of persistent negative superhumps even during the superoutburst. We performed two-dimensional period analysis of its light curves by using a method called "least absolute shrinkage and selection operator" (Lasso) and "phase dispersion minimization" (PDM) analysis, and we found that the period of negative superhumps systematically changed between a superoutburst and the next superoutburst. The trend of the period change can beinterpreted as reflecting the change of the disk radius. Read More

**Authors:**Taichi Kato, Franz-Josef Hambsch, Hiroyuki Maehara, Gianluca Masi, Francesca Nocentini, Pavol A. Dubovsky, Igor Kudzej, Kazuyoshi Imamura, Minako Ogi, Kenji Tanabe, Hidehiko Akazawa, Thomas Krajci, Ian Miller, Enrique de Miguel, Arne Henden, Colin Littlefield, Ryo Noguchi, Takehiro Ishibashi, Rikako Ono, Miho Kawabata, Hiroshi Kobayashi, Daisuke Sakai, Hirochika Nishino, Hisami Furukawa, Kazunari Masumoto, Katsura Matsumoto, Tomohito Ohshima, Chikako Nakata, Satoshi Honda, Kenzo Kinugasa, Osamu Hashimoto, William Stein, Roger D. Pickard, Seiichiro Kiyota, Elena P. Pavlenko, Oksana I. Antonyuk, Aleksei V. Baklanov, Kirill Antonyuk, Denis Samsonov, Nikolaj Pit, Aleksei Sosnovskij, Arto Oksanen, Caisey Harlingten, Jenni Tyyska, Berto Monard, Sergey Yu. Shugarov, Drahomir Chochol, Kiyoshi Kasai, Yutaka Maeda, Kenji Hirosawa, Hiroshi Itoh, Richard Sabo, Joseph Ulowetz, Etienne Morelle, Raul Michel, Genaro Suarez, Nick James, Shawn Dvorak, Irina B. Voloshina, Michael Richmond, Bart Staels, David Boyd, Maksim V. Andreev, Nikolai Parakhin, Natalia Katysheva, Atsushi Miyashita, Kazuhiro Nakajima, Greg Bolt, Stefano Padovan, Peter Nelson, Donn R. Starkey, Denis Buczynski, Peter Starr, William N. Goff, Denis Denisenko, Christopher S. Kochanek, Benjamin Shappee, Krzysztof Z. Stanek, Jose L. Prieto, Koh-ichi Itagaki, Shizuo Kaneko, Rod Stubbings, Eddy Muyllaert, Jeremy Shears, Patrick Schmeer, Gary Poyner, Miguel Rodriguez Marco

**Category:**Solar and Stellar Astrophysics

Continuing the project described by Kato et al. (2009a, arXiv:0905.1757), we collected times of superhump maxima for SU UMa-type dwarf novae mainly observed during the 2012-2013 season. Read More

**Authors:**Chikako Nakata, Tomohito Ohshima, Taichi Kato, Daisaku Nogami, Gianluca Masi, Enrique de Miguel, Joseph Ulowetz, Colin Littlefield, William N. Goff, Thomas Krajci, Hiroyuki Maehara, William Stein, Richard Sabo, Ryo Noguchi, Rikako Ono, Miho Kawabata, Hisami Furukawa, Katsura Matsumoto, Takehiro Ishibashi, Pavol A. Dubovsky, Igor Kudzej, Shawn Dvorak, Franz-Josef Hambsch, Roger D. Pickard, Etienne Morelle, Eddy Muyllaert, Stefano Padovan, Arne Henden

**Category:**Solar and Stellar Astrophysics

We report on photometric observations of WZ Sge-type dwarf novae, MASTER OT J211258.65+242145.4 and MASTER OT J203749. Read More

Mazur, Tate, and Teitelbaum gave a p-adic analogue of the Birch and Swinnerton-Dyer conjecture for elliptic curves. We provide a generalization of their conjecture in the good ordinary case to higher dimensional modular abelian varieties over the rationals by constructing the p-adic L-function of a modular abelian variety and showing that it satisfies the appropriate interpolation property. This relies on a careful normalization of the p-adic L-function, which we achieve by a comparison of periods. Read More

**Authors:**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, Peter Starr, 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

**Category:**Solar and Stellar Astrophysics

Continuing the project described by Kato et al. (2009, arXiv:0905.1757), we studied 86 SU UMa-type dwarf novae. Read More

**Authors:**Tomohito Ohshima, Taichi Kato, Elena P. Pavlenko, Hiroshi Itoh, Enrique de Miguel, Thomas Krajci, Hidehiko Akazawa, Kazuhiko Shiokawa, William Stein, Alex Baklanov, Denis Samsonov, Oksana Antonyuk, Maksim V. Andreev, Kazuyoshi Imamura, Franz-Josef Hambsch, Hiroyuki Maehara, Javier Ruiz, Shin'ichi Nakagawa, Kiyoshi Kasai, Boyd Boitnott, Jani Virtanen, Ian Miller

**Category:**Solar and Stellar Astrophysics

We report on a discovery of "negative" superhumps during the 2011 January superoutburst of ER UMa. During the superoutburst which started on 2011 January 16, we detected negative superhumps having a period of 0.062242(9) d, shorter than the orbital period by 2. Read More

In 2011 October an optical transient was reported in Pegasus as a possible nova. The object had an ultraviolet counterpart, GALEX J215818.5+241924. Read More

The aim of the present paper is to give evidence, largely numerical, in support of the non-commutative main conjecture of Iwasawa theory for the motive of a primitive modular form of weight k>2 over the Galois extension of Q obtained by adjoining to Q all p-power roots of unity, and all p-power roots of a fixed integer m>1. The predictions of the main conjecture are rather intricate in this case because there is more than one critical point, and also there is no canonical choice of periods. Nevertheless, our numerical data agrees perfectly with all aspects of the main conjecture, including Kato's mysterious congruence between the cyclotomic Manin p-adic L-function, and the cyclotomic p-adic L-function of a twist of the motive by a certain non-abelian Artin character of the Galois group of this extension. Read More

We describe a tabulation of (conjecturally) modular elliptic curves over the field Q(sqrt(5)) up to the first curve of rank 2. Using an efficient implementation of an algorithm of Lassina Dembele, we computed tables of Hilbert modular forms of weight (2,2) over Q(sqrt(5)), and via a variety of methods we constructed corresponding elliptic curves, including (again, conjecturally) all elliptic curves over Q(sqrt(5)) that have conductor with norm less than or equal to 1831. Read More

We report unfiltered photometry of SDSS J112003.40+663632.4 during the 2011 February outburst which revealed the presence of superhumps with peak-to-peak amplitude of up to 0. Read More

We report CCD photometry of the superoutburst of the dwarf nova V1212 Tau obtained during 2011 January and February. The outburst amplitude was at least 6 magnitudes and it lasted at least 12 days. Three distinct superhump regimes were observed. Read More

**Authors:**Taichi Kato, Hiroyuki Maehara, Ian Miller, Tomohito Ohshima, Enrique de Miguel, Kenji Tanabe, Kazuyoshi Imamura, Hidehiko Akazawa, Nanae Kunitomi, Ryosuke Takagi, Mikiha Nose, Franz-Josef Hambsch, Seiichiro Kiyota, Elena P. Pavlenko, Aleksei V. Baklanov, Oksana I. Antonyuk, Denis Samsonov, Aleksei Sosnovskij, Kirill Antonyuk, Maksim V. Andreev, Etienne Morelle, Pavol A. Dubovsky, Igor Kudzej, Arto Oksanen, Gianluca Masi, Thomas Krajci, Roger D. Pickard, Richard Sabo, Hiroshi Itoh, William Stein, Shawn Dvorak, Arne Henden, Shinichi Nakagawa, Ryo Noguchi, Eriko Iino, Katsura Matsumoto, Hiroki Nishitani, Tomoya Aoki, Hiroshi Kobayashi, Chihiro Akasaka, Greg Bolt, Jeremy Shears, Javier Ruiz, Sergey Yu. Shugarov, Drahomir Chochol, Nikolai A. Parakhin, Berto Monard, Kazuhiko Shiokawa, Kiyoshi Kasai, Bart Staels, Atsushi Miyashita, Donn R. Starkey, Yenal Ogmen, Colin Littlefield, Natalia Katysheva, Ivan M. Sergey, Denis Denisenko, Tamas Tordai, Robert Fidrich, Vitaly P. Goranskij, Jani Virtanen, Tim Crawford, Jochen Pietz, Robert A. Koff, David Boyd, Steve Brady, Nick James, William N. Goff, Koh-ichi Itagaki, Hideo Nishimura, Youichirou Nakashima, Seiichi Yoshida, Rod Stubbings, Gary Poyner, Yutaka Maeda, Stanislav A. Korotkiy, Kirill V. Sokolovsky, Seiji Ueda

**Category:**Solar and Stellar Astrophysics

Continuing the project described by Kato et al. (2009, PASJ 61, S395, arXiv:0905.1757), we collected times of superhump maxima for 51 SU UMa-type dwarf novae mainly observed during the 2010-2011 season. Read More

**Authors:**Bradley E. Schaefer, Ashley Pagnotta, Aaron LaCluyze, Daniel E. Reichart, Kevin M. Ivarsen, Joshua B. Haislip, Melissa C. Nysewander, Justin P. Moore, Arto Oksanen, Hannah L. Worters, Ramotholo R. Sefako, Jaco Mentz, Shawn Dvorak, Tomas Gomez, Barbara G. Harris, Arne Henden, Thiam Guan Tan, Matthew Templeton, W. H. Allen, Berto Monard, Robert D. Rea, George Roberts, William Stein, Hiroyuki Maehara, Thomas Richards, Chris Stockdale, Tom Krajci, George Sjoberg, Jennie McCormick, Mikhail Revnivtsev, Sergei Molkov, Valery Suleimanov, Matthew J. Darnley, Michael F. Bode, Gerald Handler, Sebastien Lepine, Michael Shara

**Category:**Solar and Stellar Astrophysics

The eruption of the recurrent nova U Scorpii on 28 January 2010 is now the all-time best observed nova event. We report 36,776 magnitudes throughout its 67 day eruption, for an average of one measure every 2.6 minutes. Read More

We report unfiltered photometry during the first confirmed superoutburst of the recently discovered dwarf nova, SDSS J073208.11+413008.7 and conclude that it is a member of the SU UMa family. Read More

During July 2009 we observed the first confirmed superoutburst of the eclipsing dwarf nova SDSS J150240.98+333423.9 using CCD photometry. Read More

Let f be a non-CM newform of weight k > 1. Let L be a subfield of the coefficient field of f. We completely settle the question of the density of the set of primes p such that the p-th coefficient of f generates the field L. Read More

Kolyvagin used Heegner points to associate a system of cohomology classes to an elliptic curve over $\Q$ and conjectured that the system contains a non-trivial class. His conjecture has profound implications on the structure of Selmer groups. We provide new computational and theoretical evidence for Kolyvagin's conjecture. Read More

We study p-divisibility of discriminants of Hecke algebras associated to spaces of cusp forms of prime level. We make a precise conjecture about the indexes of Hecke algebras in their normalisation which implies (if true) the conjecture that there are no mod p congruences between non-conjugate newforms of weight 2 and level Gamma_0(p). Read More

Suppose $p$ is a prime of the form $u^2+64$ for some integer $u$, which we take to be 3 mod 4. Then there are two Neumann--Setzer elliptic curves $E_0$ and $E_1$ of prime conductor $p$, and both have Mordell--Weil group $\Z/2\Z$. There is a surjective map $X_0(p)\xrightarrow{\pi} E_0$ that does not factor through any other elliptic curve (i. Read More