AAVSO Bulletin 81: Predicted Dates of Maxima and Minima of
381 Long Period Variables for 2018
Elizabeth O. Waagen, Senior Technical Assistant (Science Operations)
AAVSO, 49 Bay State Road, Cambridge, MA 02138 USA
Predicted dates for 2018 of maxima and minima of 381 long period and semiregular variables are given in this Bulletin. These dates have been determined using the AAVSO mean curves. As a convenience to the observer, approximate dates of maxima and minima for January and February of 2019 are also given. These dates are preliminary and are subject to change when the official predictions for 2019 are published. This Bulletin may also be found on the AAVSO web site page https://www.aavso.org/aavso-bulletin-81-2018.
The dates in AAVSO Bulletin 73 for 2010 were less precise than usual because observed dates for 2009 were not determined. For AAVSO Bulletin 81 for 2018, the previous method of determining the most recent observed maxima and minima dates before generating the predicted dates for 2018 was used. Thus, the dates in AAVSO Bulletin 81 have the same level of precision as in all years except 2010.
The format of the Bulletin was substantially revised for Bulletin 74, and that revised format continues. Most of the information contained in earlier Bulletins has been retained, but additional information, an online user-definable Bulletin Generator, and links to external resources (the AAVSO Light Curve Generator, International Variable Star Index (VSX), and table of AAVSO observed maxima and minima dates) have been added. The Bulletin Generator allows the user to request maxima/minima dates for a subset of stars, a constellation, a month, a RA and/or Dec range, as well as the entire Bulletin dataset. Data may be retrieved as a .pdf file, an html table, or a comma-separated file (CSV) suitable for loading into a spreadsheet. J2000.0 coordinates have replaced the Harvard Designation. To assist the observer in determining whether a star is in need of additional observations, a field ("N") has been added containing the number of observations of each star received by the AAVSO during calendar year 2017. A CSV file of the Bulletin sorted by this field from the fewest observations to the most is available.
RANGE VALUES ARE ALL VISUAL. Range values given within the symbols "< >" are average maximum and minimum visual magnitudes and are taken from the third edition of the General Catalogue of Variable Stars and its Supplements. Range values given without "< >" symbols are mean visual magnitudes of the brightest maximum and faintest minimum obtained from the data in the AAVSO International Database since 1961. The values of maximum and minimum for an individual cycle may be much brighter or fainter than the range values given in the Bulletin.
In the monthly grids, 'MAX' indicates a predicted maximum; 'min' indicates a predicted minimum. The number following 'MAX' or 'min' indicates the predicted date of maximum or minimum for each star. The word 'rising' indicates the star is brightening towards maximum and 'fading' indicates the star is fading from maximum. The color of each grid box (chosen by the user) indicates the estimated intervals during which the star will be brighter than visual magnitude 11.0 or fainter than visual magnitude 13.5, according to information supplied in AAVSO Bulletin 27.
The double-maxima stars R Cen and R Nor are not included in the Bulletin Generator or the .pdf files. The data for these stars are presented in a separate table available on the AAVSO Bulletin webpage given above. V Boo, a semiregular included with the double-maxima stars in recent years and excluded from Bulletin 78 due to excessive irregularity, is more regular and no longer displaying double-maxima behavior, and has been returned to the current Bulletin and appears in the main Bulletin table.
The Bulletin Generator was created by Dr. Matthew R. Templeton, who also rewrote the software created by Charles M. Jones and then Grant Foster to produce the Bulletin itself, and I thank him sincerely. I also sincerely thank Sara J. Beck, who rewrote and greatly expanded the capabilities of the software written by Katherine L. Davis to allow the fitting of mean curves on-screen and automatic digitization of extrema dates for all Bulletin stars and who assisted with software issues.
The observations for this Bulletin are the contributions of AAVSO members and observers in the United States and abroad. Contributions have also been made by members of the following Variable Star Associations: Agrupacion Astronomica de Sabadell (Spain); Asociacion Argentina Amigos de la Astronomia; Asociacion de Variabilistas de Espagne (Spain); Association Française des Observateurs d'Étoiles Variables (France); Association of Variable Star Observers “Pleione” (Russia); Astronomical Society of South Australia; Astronomical Society of Southern Africa, Variable Star Section; Astronomischer Jugendclub (Austria); Astronomisk Selskab (Scandinavia); British Astronomical Association, Variable Star Section (England); Bundesdeutsche Arbeitsgemeinschaft für Veränderliche Sterne e.V. (BAV) (Germany); Center for Backyard Astronomy; Koninklijke Nederlandse Vereniging Voor Weer-en Sterrenkunde, Werkgroep Veranderlijke Sterren (Netherlands); Liga Ibero-Americana de Astronomia (South America); Madrid Astronomical Association M1 (Spain); Magyar Csillagászati Egyesület, Változócsillag Szakcsoport (Hungary); Norsk Astronomisk Selskap, Variable Stjernegruppen (Norway); Nucleo de Estudo e Observacao Astronomica - Jose Bazilicio de Souza (Florianopolis, Brazil); Red de Observadores (Montevideo, Uruguay); Red de Observatores de Estrellas Variables - MIRA (Spain); Rede de Astronomia Observacional (Brazil); Royal Astronomical Society of Canada; Royal Astronomical Society of New Zealand, Variable Star Section; Svensk Amator Astronomisk Förening, Variabelsektionen (Sweden); Ukraine Astronomical Group, Variable Star Section; Unione Astrofili Italiani (Italy); URSA Astronomical Association, Variable Star Section (Finland); Variable Star Observers League in Japan; Variable Stars South (New Zealand); Vereniging Voor Sterrenkunde, Werkgroep Veranderlijke Sterren (Belgium).
The astronomical contribution of each observer is gratefully acknowledged.