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Volume 41 Number 1 JAAVSO 2013 The Journal of the American Association of Variable Star Observers V1820 Ori: an RR Lyrae Star With Strong, Irregular Blazhko Effect V1820 Ori hump evolution for nights JD 2455941 to 2455945 Also in this issue... • Very Short-Duration UV–B Optical Flares in RS CVn-type Star Systems • The Interesting Light Curve and Pulsation Frequencies of KIC 9204718 • Two New Cool Variable Stars in the Field of NGC 659 49 Bay State Road Cambridge, MA 02138 Complete table of contents inside... U. S. A. The Journal of the American Association of Variable Star Observers Editor Editorial Board John R. Percy Geoffrey C. Clayton Matthew R. Templeton University of Toronto Louisiana State University AAVSO Toronto, Ontario, Canada Baton Rouge, Louisiana Douglas L. Welch Associate Editor Edward F. Guinan McMaster University Elizabeth O. Waagen Villanova University Hamilton, Ontario, Canada Villanova, Pennsylvania Assistant Editor David B. Williams Matthew R. Templeton Pamela Kilmartin Whitestown, Indiana University of Canterbury Production Editor Christchurch, New Zealand Thomas R. Williams Michael Saladyga Houston, Texas Laszlo Kiss Konkoly Observatory Lee Anne Willson Budapest, Hungary Iowa State University Ames, Iowa Paula Szkody University of Washington Seattle, Washington The Council of the American Association of Variable Star Observers 2012–2013 Director Arne A. Henden President Mario Motta Past President Paula Szkody 1st Vice President Jennifer Sokoloski 2nd Vice President Jim Bedient Secretary Gary Walker Treasurer Tim Hager Councilors Edward F. Guinan Kevin Paxson Roger S. Kolman Robert J. Stine Chryssa Kouveliotou Donn R. Starkey John Martin David G. Turner ISSN 0271-9053 JAAVSO The Journal of The American Association of Variable Star Observers Volume 41 Number 1 2013 49 Bay State Road Cambridge, MA 02138 ISSN 0271-9053 U. S. A. The Journal of the American Association of Variable Star Observers is a refereed scientific journal published by the American Association of Variable Star Observers, 49 Bay State Road, Cambridge, Massachusetts 02138, USA. The Journal is made available to all AAVSO members and subscribers. In order to speed the dissemination of scientific results, selected papers that have been refereed and accepted for publication in the Journal will be posted on the internet at the eJAAVSO website as soon as they have been typeset and edited. These electronic representations of the JAAVSO articles are automatically indexed and included in the NASA Astrophysics Data System (ADS). eJAAVSO papers may be referenced as J. Amer. Assoc. Var. Star Obs., in press, until they appear in the concatonated electronic issue of JAAVSO. The Journal cannot supply reprints of papers. Page Charges Unsolicited papers by non-Members will be assessed a charge of $15 per published page. Instructions for Submissions The Journal welcomes papers from all persons concerned with the study of variable stars and topics specifically related to variability. All manuscripts should be written in a style designed to provide clear expositions of the topic. Contributors are strongly encouraged to submit digitized text in MS WORD, LATEX+POSTSCRIPT, or plain- text format. Manuscripts may be mailed electronically to [email protected] or submitted by postal mail to JAAVSO, 49 Bay State Road, Cambridge, MA 02138, USA. Manuscripts must be submitted according to the following guidelines, or they will be returned to the author for correction: Manuscripts must be: 1) original, unpublished material; 2) written in English; 3) accompanied by an abstract of no more than 100 words. 4) not more than 2,500–3,000 words in length (10–12 pages double-spaced). Figures for publication must: 1) be camera-ready or in a high-contrast, high-resolution, standard digitized image format; 2) have all coordinates labeled with division marks on all four sides; 3) be accompanied by a caption that clearly explains all symbols and significance, so that the reader can understand the figure without reference to the text. Maximum published figure space is 4.5” by 7”. When submitting original figures, be sure to allow for reduction in size by making all symbols and letters sufficiently large. Photographs and halftone images will be considered for publication if they directly illustrate the text. Tables should be: 1) provided separate from the main body of the text; 2) numbered sequentially and referred to by Arabic number in the text, e.g., Table 1. References: 1) References should relate directly to the text. 2) References should be keyed into the text with the author’s last name and the year of publication, e.g., (Smith 1974; Jones 1974) or Smith (1974) and Jones (1974). 3) In the case of three or more joint authors, the text reference should be written as follows: (Smith et al. 1976). 4) All references must be listed at the end of the text in alphabetical order by the author’s last name and the year of publication, according to the following format: Brown, J., and Green, E. B. 1974, Astrophys. J., 200, 765. Thomas, K. 1982, Phys. Report, 33, 96. 5) Abbreviations used in references should be based on recent issues of the Journal or the listing provided at the beginning of Astronomy and Astrophysics Abstracts (Springer-Verlag). Miscellaneous: 1) Equations should be written on a separate line and given a sequential Arabic number in parentheses near the right-hand margin. Equations should be referred to in the text as, e.g., equation (1). 2) Magnitude will be assumed to be visual unless otherwise specified. 3) Manuscripts may be submitted to referees for review without obligation of publication. © 2013 The American Association of Variable Star Observers. All rights reserved. Journal of the American Association of Variable Star Observers Volume 41, Number 1, 2013 Period Analysis of AAVSO Visual Observations of 55 Semiregular (SR/SRa/SRb) Variable Stars John R. Percy, Paul Jx Tan 1 Period Analysis of AAVSO Visual Observations of Semiregular (SR) Variable Stars. II John R. Percy, Tomas Kojar 15 Intermediate Report on January 2013 Campaign: Photometry and Spectroscopy of P Cygni Ernst Pollmann, Wolfgang Vollmann 24 The Interesting Light Curve and Pulsation Frequencies of KIC 9204718 Garrison Turner, John Holaday 34 Nine New Variable Stars in Cygnus and Variability Type Determination of [Wm2007] 1176 Riccardo Furgoni 41 V1820 Orionis: an RR Lyrae Star With Strong and Irregular Blazhko Effect Pierre de Ponthière, Franz-Josef Hambsch, Tom Krajci, Kenneth Menzies, Patrick Wils 58 Period Changes in RRc Stars John R. Percy, Paul Jx Tan 75 Recent Maxima of 61 Short Period Pulsating Stars Gerard Samolyk 85 Two New Cool Variable Stars in the Field of NGC 659 Steven P. Souza 92 Simultaneous CCD Photometry of Two Eclipsing Binary Stars in Pegasus—Part I: KW Pegasi Kevin B. Alton 97 Very Short-Duration UV-B Optical Flares in RS CVn-type Star Systems Gary A. Vander Haagen 114 Recent Minima of 273 Eclipsing Binary Stars Gerard Samolyk 122 BVRI Observations of SZ Lyncis at the EKU Observatory Marco Ciocca 134 Book Review: Scientific Writing for Young Astronomers Eric Broens 145 Table of Contents continued on following pages Abstracts of Papers and Posters Presented at the 101st Annual Meeting of the American Association of Variable Star Observers, Held in Woburn, Massachusetts, November 1–3, 2012 Variability of Young Stars: the Importance of Keeping an Eye on Children William Herbst 147 Variable Stars in the Trapezium Region: the View From Ground and Space Matthew R. Templeton 147 YSOs as Photometric Targets Arne A. Henden 148 Working Together to Understand Novae Jennifer Sokoloski 148 Campaign of AAVSO Monitoring of the CH Cygni Symbiotic System in Support of Chandra and HST Observations Margarita Karovska 148 2012: a Goldmine of Novae Arne A. Henden 149 Introducing Solar Observation to Elementary Students Gerald P. Dyck 149 AAVSO Solar Observers Worldwide Rodney Howe 149 Statistical Evidence for a Mid-period Change in Daily Sunspot Group Counts from August 2011 through August 2012, and the Effect on Daily Relative Sunspot Numbers Rodney Howe 150 Mentoring, a Shared Responsibility Timothy R. Crawford 151 66 Ophiuchi Decides to “Be” John Martin 151 V439 Cygni: Insights into the Nature of an Exotic Variable Star David G. Turner 151 Elizabeth Brown and Citizen Science in the Late 1800s Kristine Larsen 152 APASS Data Product Developments Douglas L. Welch 153 The Case of the Tail Wagging the Dog: HD 189733—Evidence of Hot Jupiter Exoplanets Spinning-up their Host Stars Edward F. Guinan 153 An Overview of the Swinburne Online Astronomy Courses Frank Dempsey 154 Percy and Tan, JAAVSO Volume 41, 2013 1 Period Analysis of AAVSO Visual Observations of 55 Semiregular (SR/SRa/SRb) Variable Stars John R. Percy Paul Jx Tan Department of Astronomy and Astrophysics, University of Toronto. Toronto, ON M5S 3H4, Canada; [email protected] Received April 26, 2012; revised June 21, 2012; accepted July 18, 2012 Abstract We have used AAVSO visual data, and Fourier analysis and self-correlation analysis, to study the periodicity of 55 semiregular (SR) variables—21 SRa and 34 SRb. According to the standard system of variable star classification, these are pulsating red giants, with visual amplitudes less than 2.5 magnitudes, which show noticeable periodicity (SRa) or less-obvious periodicity (SRb). We find that their behavior ranges from highly periodic to irregular; some are not significantly variable. We have used a simple index, based on self-correlation analysis, to show that, on average, the SRa variables have a larger component of periodicity than the SRb variables, as expected. The distributions of this index for the two groups, however, overlap considerably. Of our 55 stars, 11 definitely or possibly show two radial periods, and at least 16 definitely or possibly show a long secondary period. We also analyzed three non-SR stars: T Cet is a double-mode SRc star; T Cen is an RVa star which should be reclassified as RVb; V930 Cyg is an irregular (Lb) star with a strong 250-day period.

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